AB stands for Aurora borealis (which means “northern lights”). Aurora borealis rhinestones have a special iridescent finish that shines with many colors. The iridescent surface is a result of a very thin layer of metallic atoms that have been deposited on the lower surface of the stone. This process was invented in 1955 by the Swarovski company together with Christian Dior.
Abalone is a mollusk whose shell is iridescent on the inside. Abalone is a source of mother of pearl, which is used in jewelry making.
Fashion accessories and their jewelry counterpart referred to as costume jewelry are items that used as fashion’s complementary. Accessories help to bring up the spot that one wants to highlight in a dress or apparel.
Acroite is a rare, colorless variety of tourmaline.
Acrylics are a type of thermoplastic, and include transparent and opaque in varied colors. Some commonly-known acrylics are Lucite and Plexiglas. The bangle above is made of confetti Lucite.
Adamantine means having a luster like that of a diamond.
Adularia is a common type of moonstone, a whitish-bluish semi-translucent stone. Adularia is usually set as a cabochon. Adularia was very popular early in the 20th century and was extensively used in Art Nouveau jewelry. Adularia has a hardness of 6 and a specific gravity of 2.57.
Aventurine is a shimmering quartz stone that ranges in color from yellow to red to light green to light brown. The shimmer is caused by tiny metallic particles (mica) within the stone.
Agate is a variety of chalcedony (a family of microcrystalline quartz). Agate is a very common stone that is often used in jewelry. It is found in a wide range of colors, including black, gray, brown, reddish, green, pink, blue, and yellow. Agate can be flecked with color and is often banded, exhibiting layers of quartz. Agate is porous and takes dye easily; it is frequently dyed to enhance the coloration and the banding. White agate was used often in Victorian jewelry, mostly as a background. Moss agate has green, red or black dendrite inclusions. Onyx is agate whose bands are parallel. Eye agate has banding arranged in concentric circles. Agate has a hardness of 6.5 to 7 and a specific gravity of 2.6. The agate pin above is from Miracle.
African jade (also called Transvaal jade) is a misnomer for massive green grossular garnet that is mined in South Africa; it is not jade, but does look like jade. It can be light green, white, or pink
Alexandrite is a mineral (a type of chrysoberyl) that appears to be different colors depending on whether it is viewed in natural or artificial light. Alexandrite appears to be red when seen in candle light and blue to green when seen in fluorescent light. Alexandrite was discovered on the birthday of the Russian Czar Alexander II, and it was named in his honor. Alexandrite is mined in Russia, Brazil, Burma, Ceylon, and Rhodesia. Laboratory-produced alexandrite is common, and it is often sold as natural alexandrite. Alexandrite has a hardness of 8.5 and a specific gravity of 3.64-3.74.
The “Alexandrite Effect” is a phenomenon in which a stone appears to be different colors depending upon the type of light it is viewed in. For example, the stone alexandrite appears to be red when seen in candle light and blue to green when seen in fluorescent light. Many other stones exhibit the “Alexandrite Effect,” including garnet and sapphire.
An alloy is a combination of two or more metals. Common alloys used in jewelry are: gold under 24 Kt (mixed with silver, copper, and/or other metals), sterling silver (92.5% silver, 7.5% copper), brass (roughly half copper, half zinc), bronze (at least 60% copper with tin and perhaps other metals), and pewter (tin, lead, antimony, and a bit of silver or copper).
Almandine is a type of violet-tinged variety of garnet that ranges in color from deep red to reddish-brown. Almandine is the most common kind of garnet. Star garnets are almandine that exhibit an asterism. Almandine has a hardness of 7.5 and a specific gravity of 3.85-4.20.
Alpaca (also spelled alpacca) is an alloy consisting of mostly copper (roughly 60 percent), and approximately 20 percent nickel, about 20 percent zinc, and about 5 percent tin. This metal is a silver substitute.
Amber is translucent fossilized tree resin (from conifers), a natural hydrocarbon that comes in many colors, including yellow, reddish, whitish, black, and blue. Amber is flammable. Rubbing amber produces static electricity. The word electricity comes from the Greek word for amber, “elektron.” It used to be thought that amber possessed magical powers that protected the wearer from evil. Pressed amber consists of small pieces of amber that have been fused together to form a larger piece. Fake amber is easily made from plastics, and buyers must beware of cheap imitations sold as natural amber. Amber has a hardness of 2.5 and a specific gravity of 1.05-1.10.
An American ruby is actually a pyrope garnet (and not a ruby at all).
Amethyst (Greek for “not drunken”) is a form of the mineral quartz, and is a relatively common gemstone. Amethyst is usually purple, but can range in color from pale lavender to a very deep, reddish purple to a milky color to green. Deeper-colored amethysts are more highly valued. The ancient Greeks believed that amethyst made one immune to the effects of alcohol. Synthetic amethysts are hard to distinguish from the real stone.
Ametrine is a variety of quartz, a mixture of amethyst and citrine. Ametrine is partially purple and partially orange-yellow.
Amorphous means without form. An amorphous gem, like jet, amber, or ivory, does not have a regular internal structure, like those gems that fall within the seven crystal systems.
An amulet is a protective charm that is worn. It is worn in the hope of protecting the wearer from evil or illness or to bring the wearer good luck.
Angelite (CaSO4); it is a pale blue variety of calcium sulfate = anhydrate (it is gypsum that has lost water and crystallized). The stone is quite brittle; crystals are transparent to translucent. Angelite stone has a hardness of 3 to 3.5 (quite soft) and a specific gravity of 2.9 – 3.0.
Angelskin coral is a pale pink coral, from deep sea coral. Angelskin coral is one of the most valued colors of coral (red is also highly prized). Coral is an animal that grows in colonies in the ocean. Coral polyps secrete a strong calcium structure that is used in jewelry making. Coral ranges in color from pale pink (called angelskin coral) to orange to red to white. In jewelry making, coral is either carved into beads, cameos, or other forms, or is left in its natural branch-like form and just polished. It used to be thought that coral protected the wearer, so it was a traditional gift to children. Coral has a hardness of about 3.5 and a specific gravity of 2.6 to 2.7. Since it is composed of calcium carbonate, coral will effervesce if touched with acid. Imitation coral is made from glass, porcelain, or plastic.
Annealing is the process of heating a metal and then cooling it to make it more workable. As metal is worked (hammered, rolled, etc.), stresses make the metal brittle (the metal molecules are pulled into random structures during the working). Annealing the metal make the metal re-crystallize, putting the molecules in an orderly structure. The temperature (and amount of time it takes) for annealing a metal depends on what metal or alloy it is. Large pieces are annealed in an annealing oven; small pieces are annealed using a blow-torch.
Anodized metal has been through an electrochemical process which changes the molecular structure of the surface layer, giving it a thin, protective film. In the anodization process, the metal is placed in an acid bath (at the “anode” or positive end of the electrical circuit) and an electrical current is passed through the tank. This process causes a controlled oxidation of the metal’s surface to occur (oxygen atoms bond to surface atoms of the metal). Aluminum is often anodized, as is magnesium, titanium, and tantalum. Anodized metal has a lustrous sheen; the anodizing process can produce colorful surfaces.
Apache tears (a type of obsidian) is a volcanic glass that is usually black, but is occasionally red, brown, gray, green (rare), dark with “snowflakes,” or even clear. This glassy, lustrous form of obsidian is found in lava flows in the southwest USA. Obsidian is formed when viscous lava (from volcano’s) cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35. The pin above is mahogany (brown) obsidian.
Aquamarine is a transparent, light blue or sea-green stone that is porous. Today, blue aquamarines are more highly valued, but this was not true in the past, when sea-green stones were prized. Heat-treatment turns greenish stones bluer. The best aquamarines come from Brazil. Large aquamarines are relatively common. Aquamarines are usually faceted but when they are cabochon cut, a cat’s eye effect or asterism may appear. Aquamarines belong to the beryl family of stones. Aquamarine has a hardness of 7.5-8 and a specific gravity of 2.65-2.85.
Aqua regia is a 3:1 mixture of hydrochloric acid and nitric acid. Aqua regia is used to test gold and platinum; it is just about one of the few substances that can dissolve gold and platinum.
Aragonite is a mineral that is rarely used for jewelry. It is transparent to translucent and can range in color from honey-colored to pale reds, blues and greens to clear or white. It forms hexagonal crystals, pyramidal crystals, chisel shaped crystals, and other shapes. Aragonite has a hardness of 3.5-4 (relatively soft) and a specific gravity of 2.9 g/cm3.(average). Its chemical composition is CaCO3 (it is a form of Calcium Carbonate). Aragonite is named for Aragon, Spain, where it was first found in 1790. Aragonite is also found in many other European, North African, and some North American locations.
An arcade setting (also called coronet or claw setting) is one in which the stone is held in by many metal claws around a metal ring.
Arctic opal is a blue-green stone that is a mixture of azuritea and malachite; it is not a type of opal at all. Arctic opal is mined in the Wrangle Mountains and the Chugach Mountains of Alaska, USA (near Anchorage).
Arkansas stone is an abrasive used in jewelry making. It is used to smooth metals.
Art Deco was a style popular from the mid-1910’s until the mid-1920’s. This style originated in Paris, France. Art Deco pieces are characterized by geometric lines and angles, with very few curves. This art movement eventually became bolder and evolved into Art Modern.
Art Nouveau was a style popular from roughly 1895 until World War I. Art Nouveau pieces are characterized by curves and naturalistic designs, especially depicting long-haired, sensual women. Louis Comfort Tiffany made archetypal Art Nouveau pieces.
A highly-skilled craftsman who exhibits great manual dexterity.
ARTS AND CRAFTS
Arts and Crafts was an artistic movement that produced hand-crafted pieces toward the end of the 1800’s. Pieces purposely look hand-made, incorporating hammer marks and simple cabochon settings. The Arts and Crafts movement also revived the art of enamel.
An assay is a test of the purity of an alloy. A tiny piece of metal is scraped from the piece and the percentage of gold or silver is determined. Official assay offices determine whether a piece qualifies for an appropriate hallmark.
Joseph Asscher was an eminent diamond cutter who cut the 3,106 carat Cullinan diamond. Asscher worked in Amsterdam. In 1902, his company, the Asscher Diamond Co., developed and patented the Asscher cut, a squarish step cut with an almost octagonal outline. This new cut enhanced the fire and light of the stone; it had a small table, a high crown, wide step facets, a deep pavilion and square culet. This cut became very popular in Art Deco jewelry and was a forerunner of the emerald cut. Recently, the Royal Asscher Diamond Co. resumed production of the original Asscher cut diamonds.
An asterism is a star-like luminous effect that reflects light in some gemstones, like star.
An Australian ruby is actually a pyrope garnet (and not a ruby at all).
Aventurine feldspar is also called Sunstone (a variety of oligoclase). This gemstone varies from golden to orange to red-brown, and can be transparent or translucent. Sunstone is metallic-looking due to sparkling red, orange or green crystalline inclusions (these are hematite or goethite crystals). Sunstone is found in Canada, the USA (in Oregon, India, Norway, and Russia) This brittle stone has a hardness of 6 and a specific gravity of 2.63 – 2.67. Sunstone is not enhanced.
Aventurine quartz is a type of quartz that has sparkling flecks (inclusions) of mica or iron. These colors of this stone include red-brown, yellow, gray, and green. Aventurine quartz has a hardness of 7 and a specific gravity of 2.64-2.69. This stone is usually cut with a flat or rounded surface to maximize its sparkle. Aventurine quartz is found in India, Russia, and Tanzania.
The Japanese name for abalone pearls is Awabi pearls.
Axinite is an unusual, lustrous stone that is brown, yellow, blue, green or gray. Violet axinite is rare (and from Tasmania). It has both transparent and translucent varieties. Axinite is dichroic. Axinite has a hardness of 7 and a specific gravity of 3.3. Axinite is a boro-silicate of aluminum and calcium. It is used only as a mineral specimen and not in jewelry.
AXIS OF SYMMETRY
An axis of symmetry (also called a rotational axis) is an imaginary line around which an object can be rotated a certain number of degrees and look like the original shape. When two planes of symmetry intersect, they form a straight line, which is an axis of symmetry.
Azurite is a beautiful copper-based blue mineral that is often used in jewelry. The color ranges from very deep blue to pale blue. Azurite has also been used as a dye for paints and luxury fabrics. Azurite is hydrated copper carbonate; its chemical formula is Cu3 (CO3)2(OH) 2. Malachite (another copper-based mineral) and azurite are often found together. Azurite has a hardness of 3.5 to 4 (relatively soft) and a specific gravity of 3.7 to 3.9. Azurite is found in massive monoclinic crystals in Australia the southwestern USA, France, Mexico, Morocco, Namibia, Zaire, and Europe. Azurite is sometimes coated with a colorless wax or impregnated with plastic in order to enhance the color and increase the hardness.
Articulated: Jewelry fashioned with hinges to provide movement and flexibility.
Baffa diamond is actually rock crystal and not a real diamond.
A baguette cut is a stone (usually a diamond) that has been cut into a long, rectangular shape. Baguette means “stick” or “rod” in French.
Bakelite (also called catalin) is a dense, synthetic resin that was used to make jewelry, game pieces, and many other things. Bakelite was patented by L.H. Baekeland in 1907. Bakelite plastic is made from carbolic acid and formaldehyde. Bakelite pieces are molded, extruded, or carved. When one Bakelite color is inlaid into another, interesting designs like polka dots can be made. Bakelite was first used to imitate amber. The bangle above is “butterscotch” bakelite
A bail is a triangular finding that attaches a pendant to a necklace.
A band is a ring that is made from a thin, flat, ribbon-like strip of material (usually metal). The band can be unadorned or decorated. Wedding rings are often bands.
Banded agate is a type of agate with distinct layers of color.
A bangle is a stiff bracelet. Some bangles have a hinge while others are solid and must be slipped over the hand.
BAR AND RING CLASP
A bar and ring clasp (also called a toggle clasp) is a jewelry fastener in which a bar can be inserted into a ring to fasten a piece of jewelry. It is used to attach the two ends of a necklace or bracelet.
‘Baroda Gem’ is a trade name for a colorless glass stone with a foil back.
Baroque is a term that refers to irregularly-shaped stones or pearls.
Baroque pearls are irregularly-shaped pearls. Baroque pearls can be natural or artificial.
A bar pin (also called a bar brooch) is a long pin that is worn horizontally.
A barrel clasp is a jewelry fastener that resembles a barrel. The two pieces of this clasp screw together. It is used to attach two other rings or links of a necklace or bracelet.
A barrette is an ornament worn clipped into the hair.
Base metal refers to non-precious metals. Base metals include copper, zinc, tin, and lead. BASSE-TAILLE Basse-taille (meaning “low cutting” in French) is an enameling technique in which the underlying metal (usually gold or silver) is carved in low relief (the metal’s surface is cut away by engraving or chasing, producing a sculpted surface). The highest point of the relief carving is below the surface of the surrounding metal. Translucent enamels are applied over the carved metal, allowing the design to remain visible through the enamel. The hue of the enamel changes with the depth of the glaze, resulting in subtle variations in color over the high and low design elements.
A baton is a stone that is cut in a long, thin rectangular shape. A baton is larger than a baguette.
A bayadre is a pearl necklace that has many strands of pearls twisted together.
Beads are small objects, each with a hole through it for stringing. Beads are made of glass, stones, wood, plastics, seeds, and ceramics.
A bell cap is a jewelry finding that is used to convert a hole-less bead or stone with into a pendant. A bell cap is glued onto the bead or stone and had a loop for attaching to the piece of jewelry.
Benitoite is a rare, blue gemstone that is found mostly in the San Benito River in San Benito County, near Coalinga, California (lesser quality benitoite is found in Mont St. Hilaire, Quebec, Canada). Benito means “blessed” in Spanish. This gemstones is strongly diachronic; although Benitoite is blue when viewed from most directions, it appears colorless when viewed in a single direction (the c-axis). Some unusual Benitoite is blue, but pink or orange when viewed through the c-axis. Benitoite is BaTiSi3O9 (Barium Titanium Silicate); no one is sure what element causes the blue color of benitoite, but it may be iron. Benitoite has a hardness of 6 – 6.5, a specific gravity of 3.68, and a refractive index of 1.757 – 1.804. Benitoite has a very unusual crystalline shape – it is the only known ditrigonal-dipyramidal crystal. Large stones (over 1 or 2 carats) are exceedingly rare. Benitoite was discovered in California in 1907, either by Mr. Hawkins and T. Edwin Sanders or James Marshall Couch (the story is in dispute). Heat-treated benitoite becomes orange; these stones are more expensive. Benitoite is California’s official state gemstone (since 1985).
Beryls are a family of gemstone that include emerald, aquamarine, beryl (green), red, morganite (yellow), and heliodor (pink). Beryl has a hardness of 7 – 8, a specific gravity of 2.6 – 2.9, and the chemical formula Be3Al2SiO6. Internal flaws in beryl gems can be hidden by treating the stone with oil (this is often not disclosed to the buyer).
A surface that has been cut at an angle less than 90 degrees.
The bezel is the part of a cut stone that protrudes above the edge of a setting. The bezel is also known as the crown.
A bezel setting is a way of setting a stone in which the stone is held by a band of metal around the outside of the stone.
A bib necklace (also known as a collarette) is a short necklace with flowing ornaments in the front.
Birefringence is another name for double refraction. In doubly-refractive stones, the light entering the stone is split into two light rays, and the rays travel in different paths. These stones have more than one refractive index. Calcite, peridot, zircon, tourmaline, and titanite are doubly-refractive stones.
In the 1930’s, the British and U.S. jewelry industries assigned stones to the months of the year as follows: January – Garnet February – Amethyst March – Aquamarine April – Diamond May – Emerald June – Pearl or Moonstone July – Ruby August – Peridot September – Sapphire October – Opal November – Topaz or Citrine December – Turquoise or Zircon
Biwa pearls are freshwater pearls from Lake Biwa in Japan. These irregularly-shaped pearls are smoother and more lustrous than most other freshwater pearls.
BLACK HILLS GOLD
Black Hills gold is gold jewelry that is made (but not always mined) in the Black Hills area of South Dakota, USA. Gold was first discovered in that area about 1874 by Horatio N. Ross. E.O Lampinen opened the Black Hills Jewelry Manufacturing Company in Deadwood, South Dakota in the early 1900’s. Modern day Black Hills jewelry often has a three-color (yellow gold, pink gold and green gold) grape leaf and vine pattern. There are many companies that make Black Hills jewelry today, but by law, their creations must be made from Black Hills gold. This jewelry is often (but not always) 10 Karat gold.
Black moonstone is a type of labradorite and not true moonstone.
Black opals are a valuable type of precious opals with a dark ground color. They are luminous, iridescent, and frequently have inclusions of many colors (“fire”). Opal is a mineral composed of silica (and some water) and is a species of quartz. The rainbow-like iridescence is caused by tiny crystals of cristobalite. Many opals have a high water content – they can dry out and crack if they are not cared for well (opals should be stored in damp cotton wool). Opals have a hardness of 5.5 to 6.5 and a specific gravity of 1.98-2.50. Black opals are found in Australia.
Black pearls (also called Tahitian pearls) are dark-colored pearls. They are produced by the large, black-lipped pearl oyster Pinctada margaritifera (also called the Tahitian black pearl oyster), a mollusk found in the tropical Indo-Pacific Ocean. Black pearls come in many colors, including many body shades and overtone tints including gray (light gray to almost black), peacock green (especially valuable), aubergine (eggplant), and deep brown. The color of the dark nacre is determined by the minerals in the oyster’s diet (plankton) and in its environment. Many “black pearls” are dyed or irridiated to enhance or change their color; it is difficult to tell a natural pearl from a treated pearl. Tahitian pearls are graded on six factors: 1.Shape (round is most valued), 2.Size (the larger the better), 3.Surface Quality= (clean is superior to blemished), 4.Luster (the more high-gloss luster the better), 5.Nacre Thickness (thicker is better and longer lasting), and 6.Color (overtones atop the body color add value to the pearl. The most sought-after color is peacock green and darker colors are more valuable Overtone colors include blue, pink, gold, silver, aubergine, and peacock green).
BLACK STAR DIOPSIDE
(BLACK STAR OF INDIA) Black star of India is another name for Black Star diopside (CaMgSi2O6), an opaque black gem with a white, four-rayed star (an asterism). It has a hardness of 5.5 and a specific gravity of 3.3 – 3.6. These stones are found mostly in India. Stones are generally cut cabochon and are not enhanced.
Bleaching is a process in which a gemstone’s color is removed using a bleaching agent.
A blister pearl (also called a bouton pearl) is a pearl that developed attached to the inside of a mollusk’s shell. This type of pearl must be cut off the shell, and is therefore hemispherical. Because of their shape, blister pearls are mostly used for earrings.
Bloodstone (also called heliotrope) is an inexpensive type of chalcedony that is green with red highlights (caused iron oxide). Bloodstone is porous and relatively soft.
Blue diamonds are rare, fancy diamonds and are quite valuable. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 – 2.419.
Blue gold is gold with a bluish tinge. It has been alloyed with a mix that includes iron.
A bodkin is a heavily jeweled, Renaissance era hairpin.
A “Bohemian diamond” is not a diamond at all, it is actually a rock crystal.
A Bohemian ruby is actually a pyrope garnet (and not a ruby at all).
A bolt ring (also known as a spring ring) is a hollow circular metal fastening ring with a spring opening. It is used to attach two other rings or links of a necklace or bracelet. The bolt ring was invented early in the 1900’s
Bonding is a process in which a colorless bonding agent (like plastic) is applied on and into a porous gemstone to make the stone more durable and have an enhanced appearance.
Bone is animal bone, carved to make beads, pins, bangles, etc. It superficially resembles ivory, but has a less-complex characteristic internal patterns and a yellowish color.
A bookchain is a metal chain with rectangular links of folded metal, each of which looks like a little book. This style dates from the Victorian Era, when these chains held lockets.
Bort is a term for industrial grade diamonds.
Botanical gems are minerals that form from plants or plant material. Some botanical gems include amber (fossilized tree resin), coconut pearl (a rare, shiny, calcareous, pearl-like mineral that forms inside the coconut, Cocos nucifera), and pearl opal (also called Tabasheer opal, which form in injured bamboo joints).
A bouton pearl (also called a blister pearl) is a pearl that developed attached to the inside of the mollusk’s shell. This type of pearl must be cut off the shell, and is therefore hemispherical (half a sphere). Because of their shape, blister pearls are mostly used for earrings.
A bracelet is an ornament worn wrapped around the wrist. Types of bracelets include solid and hinged bangles, expansion, cuff, beaded, charm bracelets, Yurman-style and, and link bracelets.
Brass is a metal alloy containing (at least 50%) copper and zinc.
A Brazilian chain (also called a snake chain) is a metal chain made up of a series of small, linked cups.
Brilliant cut stones have 56 facets, 32 facets are above the girdle, 24 are below. Most modern-day diamonds are brilliant cut since it maximizes the amount of reflected light from the stone (its natural fire). The brilliant cut was introduced in the 1600’s.
A briolette (or drop cut) is a pear-shaped cut gemstone with triangular facets on top. This type of stone makes a nice pendant.
A brooch (also called a pin) is an ornament that can be pinned to a garment.
Bronze is a metal alloy containing (at least 60%) copper plus tin and other metals.
A brushed finish on a metal’s surface is made by rubbing a stiff metal brush across the surface of jewelry, slightly reducing the metal’s reflectivity.
Bruting is the first step in cutting a diamond. Bruting involves shaping the girdle, which gives the stone its basic shape.
Bubbles are spherical or tear-shaped bubbles of gas captured in glass stones. Bubbles can also be found in resins (like plastics and amber), and much less-frequently in minerals (like quartz, emerald, and topaz). Looking for bubbles is one way to determine if a gem is glass or a gemstone.
A bugle bead is a long, thin, tube-shaped glass bead.
A bulla is an ancient Roman pendant that consists of a rounded container holding an amulet (a good luck charm). The bulla is worn on a strap around the neck.
When the gemstone is held in place without the use of prongs or beads and is set flush with the setting’s surface.
A cabochon is a stone that has a rounded, domed surface with no facets. A cabochon garnet is also called a carbuncle.
Cairngorm is a yellow-brown type of smoky quartz that is often used in traditional Celtic jewelry. Cairngorm is not Scottish topaz. The supply of cairngorm is virtually exhausted, so heat-treated Brazilian amethyst is used as a substitute in Scottish jewelry.
Calcite (Calcium Carbonate, CaCO3) is a very common mineral that comes in a wide variety of forms, shapes and colors. The trigonal crystals range from translucent to transparent. Transparent calcite exhibits a double refraction effect (when you look through the crystal, single items are doubled). Calcite has a hardness of 3 (most forms), a specific gravity of about 2.7, a refractive index of 1.49 and 1.66, and a white streak.
Calibre-cut stones are small stones that are cut into special shapes that are meant for use in commonly-used designs. These stones usually have step-cut facets and are generally rectangular shaped.
A California ruby is actually a pyrope garnet (and not a ruby at all).
A cameo is a relief carving (a carving that comes up above the surface) on a shell or stone. In multi-colored cameos, a layered substrate is used (with two different colors), and when part of the upper layer is carved away, the second color emerges as the background. Cameos are frequently portraits of women. Many imitation cameos are made from pressed glass or plastic; some of these use two different colors, like the imitation cameo pictured above.
A cameo habille (meaning “dressed cameo” in French) is a “jewel within a jewel,” a cameo in which the subject carved in the cameo (usually a woman) is wearing a miniature piece of jewelry (like a tiny diamond necklace with a stone embedded in the cameo).
Canary diamonds are diamonds that have a deep yellow color. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 – 2.419
Cape amethyst is a form of amethyst that is layered or striped with milky quartz. Cape amethyst is a translucent gemstone that ranges from light- to medium-purple and has white bands.
A measure of weight used for gemstones. Not to be confused with “karat”, which is a measure of gold alloy purity. Often abbreviated as “ct.” one carat is equal to 200 milligrams (one fifth of a gram). Gemstones are measured to the nearest hundredth carat (known as a “point’). A hundredth of a carat is called a point. For example, a .25 carat stone would be said to have twenty five points. A carat is one of the 4 Cs of diamond grading. The others being Clarity, Cut, and Color. The carat unit was introduced in 1907.
A carbonardo is a rare type of opaque black diamond; they are not used for jewels, but for items like drilling bits and abrasive wheels. They were once thought to have been formed as a result of a comet impact 2 billion years ago, but this is no longer thought to be true. The largest diamond ever found was a carbonardo that weighed over half a kilogram. Carbonadoes are found in Bahia, Brazil, South America. Unlike other diamonds, carbonadoes are not found in a crystallized form – they are found in irregular or rounded fragments. Carbonadoes have a hardness of 10 and a specific gravity (density) of 3.1-3.3. Diamonds have a very hard polycrystalline carbon structure.
A carbuncle is a cabochon garnet.
Carnelian (also called cornelian and carneole) is a reddish form of chalcedony (a type of quartz). This translucent stone has a waxy luster. The best carnelian is from India. Most commercial carnelian is really stained chalcedony. Carnelian has a hardness of 7 and a specific gravity of 2.61.
Grandson of Louis Francois Cartier, the founder of the House of Cartier in Paris—which fast became one of the world’s leading jewelry firms. Louis was responsible for popularizing the use of platinum in jewelry during the early 1900s. Famous for his garland designs during the Edwardian period, Louis Cartier also was influential during the Art Deco period, as well as the designer responsible for inventing the first wristwatch.
Casting is the process in which metal is shaped by melting it and pouring it into a mold. This process has been used for thousands of years. Molds are made from many materials, including plaster compounds. Some different methods of casting include the lost wax process, centrifugal (or investment) casting, and sand casting.
A cathedral ring setting is a simple band that arches when seen from the side (like the arches of a cathedral).
CAT’S EYE CHRYSOBERYL
Cat’s eye (chatoyant chrysoberyl) is a yellow to green-yellow to gray-green stone with a bright, pupil-like slit that seems to move slightly as the stone is moved. Most Cat’s eye is cut as cabochons to maximize the distinctive pupil-like effect. Most cat’s eye chrysoberyl is found in Brazil. Cat’s eye chrysoberyl has a hardness of 8.5. This stone is sometimes enhanced by irradiation (this process improves the color and accentuates the stone’s asterism).
Celtic jewelry was made by the Celts in Ireland, Wales, Scotland, and Brittany. The Celts used bronze, silver and gold in their jewelry and stones like cairngorm and amethyst. Circular brooches with a long, hinged pin, called pen annular brooches, date from ancient times. The earliest-known piece of Celtic jewelry is the Hunterston brooch from 700 A.D.
The prominent precious gemstone which is the centerpiece of a ring setting.
CFW is an abbreviation for cultured freshwater pearls.
Chalcedony is a family of minerals (microcrystalline quartz) that are often milky to gray to bluish in color. Chalcedony includes agate, carnelian (waxy red), chalcedony (blue), chrysoprase (green), onyx (black and white), bloodstone, sard (brownish-red), jasper (hornstone), seftonite, and others. Chalcedony is porous and translucent. Chalcedony has a hardness of 6.5-7 and a specific gravity of 2.6.
(meaning sunken enamel) Champleve (also called email champleve) is a method of applying enamel to metal in which the design is first outlined on the metal surface by cutting lines into the surface. The engraved grooves are then filled with enamel, then fired to a glassy sheen, and polished. Champleve is similar to cloisonne, but not as delicate.
An earring with a drop that dangles like a chandelier.
Channel set jewels rest in a metal channel, held in only by a slight rim which runs along the edges of the channel. Channel set jewels are usually round or baguette shaped.
From her first millinery shop, opened in 1912, to the 1920s, Gabrielle ‘Coco’ Chanel rose to become one of the premier fashion designers in Paris, France. Replacing the corset with comfort and casual elegance, her fashion themes included simple suits and dresses, women’s trousers, costume jewelry, perfume and textiles.
A decorative pendant or trinket to be worn on a bracelet, necklace or earring.
A link bracelet to which charms can be attached.
Chasing is a type of metal decoration in which the metal is manipulated using a hammer and a punch, resulting in an effect similar to engraving or embossing.
A chaton is a stone with a reflective metal foil backing.
A chaton setting (also called coronet or arcade setting) is one in which the stone is held in by many metal claws around a metal ring.
Chatoyancy is the lustrous, cat’s eye effect seen in some cabochon stones, like cat’s eye, tiger’s eye (pictured above), and sometimes in other stones, like aquamarine. In chatoyancy, light is reflected in thin bands within the stone. Chatoyant stones are cut in cabochon to maximize the lustrous effect.
Chenier is fine, hollow tubing that is used in the production of some jewelry findings (like clasps and joints), and lately, in the actual production of jewelry. The hollow tubes are lightweight and save in the use of gold. The tubes are hard to bend when they are empty, so a metal rod is inserted before bending, facilitating the bending.
A choker is a type of necklace that fits tightly around the neck. Chokers are from 14″ to 16″ in length.
Chrome diopside is an emerald-green colored gemstone. It is a chromium-rich variety of the common mineral diopside (Calcium magnesium silicate). Chrome diopside has a hardness of 5 to 6 and a specific gravity of 3.3 to 3.6.
Chromium is a hard, shiny, gray-white metal. This metal resists corrosion very well and is used in costume jewelry as a coating over other metals.
Chrysoberyl is a hard stone that ranges in color from yellow, to brown, to green. Some chrysoberyls include alexandrite and cat’s eye.
Chrysolite is a name used for many stones. During Victorian and Edwardian time, it referred to green-yellow chrysoberyl. It can also refer to peridot. Long ago, the name was used to refer to almost any yellowish gem.
Chrysoprase is the most valued variety of the mineral chalcedony (microcrystalline quartz) that contains nickel, giving it an apple-green color. Chrysoprase is porous and translucent. It is usually cut as a cabichon, and has been used since ancient times. Chrysoprase has a hardness of 7 and a specific gravity of 2.6. Chrysoprase is mined in Australia, Russia (the Ural Mtns.), Brazil, and the western USA. Chrysoprase is sometimes called “Australian jade,” but it is not related to jade. Hard-to-detect imitation chrysoprase is made by staining agate with chromium salts.
Cire perdu (French for “lost wax”) is a process of casting metal in which the original model is sculpted in wax. The wax is entombed in clay, and the wax is then melted out, producing a hollow mold. The mold is then filled with molten metal. The clay is broken off and the cast metal remains.
Citrine (from the French for “lemon”) is a rare, yellow type of quartz, a semi-precious stone that ranges in color from pale yellow to orange to golden brown. The best quality citrine is found in Brazil. Many of the stones sold as citrine are actually heat-treated amethysts. Citrine has a hardness of 7 and a specific gravity of 2.65.
Clarity is the clearness of a gemstone, or the lack of internal flaws. The clarity scale for diamonds runs from FL (flawless, with neither internal nor external flaws), to I3 (having many clearly visible imperfections using only the naked eye). A ten-power loupe is used to examine a diamond for clarity.
A clasp is a fastener that can open and close, attaching two things together (for example, the two ends of a necklace, or a pin to a garment). The clasp on a piece of jewelry can tell you a lot about the piece, including giving an indication of its age (by determining when that particular type of clasp was invented and looling at the wear on the clasp), its quality (better quality pieces generally have better-quality clasps), and its composition and manufacturer (the clasp is often where the maker’s stamps are). For example, the spring ring clasp was invented early in the 1900’s; jewelry made prior to 1900 or so will not have a spring ring clasp. Some other common clasps include the lobster claw clasp, the box clasp, the barrel clasp, the fold-over clasp, the hook-and-eye clasp, and the bar and ring toggle clasp.
A claw is a metal prong that holds a stone securely in a setting.
A claw setting is one in which a series of metal prongs (called claws) holds a stone securely in a setting (the claws grips the stone just above the girdle of the stone), with no metal directly under the stone (it is an open setting). This setting lets light in under the stone, so this type of setting is usually used for transparent, faceted stones. The modern-day claw setting became popular in the 1800’s.
Cleavage is the natural in which way a mineral breaks, along certain planes based on its internal crystalline structure.
Cloisonne is a method of applying enamel to metal in which the design is first outlined on the metal surface using a metal wire. The space between the wires is filled with enamel and then fired to a glassy sheen.
A closed setting is one in which the back of the stone is not exposed (the metal is not cut away behind the stone).
A cloud is a type of inclusion in some gemstones that has a milky appearance (and greatly affects the value of the stone). A cloud is usually composed of a cluster of tiny inclusions.
A cluster setting is one in which small stones or pearls are set around a larger stone.
A collet setting is a very early method of setting gemstones. A collet is a thin, round band of metal that goes all around the stone. One edge of the metal is crimped over the edges of the stone and the other edge is soldered to the metal of the jewelry, holding the stone in place. This closed setting sometimes also had metal claws along the outside to hold the stone even more securely (the claws were not used much after the 1200’s and 1300’s.
A collarette (also known as a bib necklace) is a short necklace with flowing ornaments at the front.
A composite suite is a piece of jewelry that can be taken apart into two or more pieces which can also be worn. For example, a necklace may be disassembled into two bracelets.
Confetti lucite is transparent plastic with glitter or other small pieces of material within it. Whimsical bangles, earrings, pins, necklaces and other jewelry have been made from confetti lucite.
Usually used in reference to 16 th century Spanish soldiers who conquered the civilizations of Mexico, Central America, and Peru.
Copper is a soft metal often used in jewelry. It is used in making bronze, brass, and gold alloys. The enameled copper leaf pin above is marked Matisse, from the “Renoir of California” jewelry company.
Coral is an animal that grows in colonies in the ocean. Coral polyps secrete a strong calcium structure that is used in jewelry making. Coral ranges in color from pale pink (called angelskin coral) to orange to red to white to black. The most valued colors are deep red (called noble coral) and pink. In jewelry making, coral is either carved into beads, cameos, or other forms, or is left in its natural branch-like form and just polished. It used to be thought that coral protected the wearer, so it was a traditional gift to children. Coral has a hardness of about 3.5 and a specific gravity of 2.6 to 2.7. Since it is composed of calcium carbonate, coral will effervesce if touched with acid. Imitation coral is made from glass, porcelain, or plastic.
A coronet setting (also called chaton or arcade setting) is one in which the stone is held in by many metal claws around a metal ring.
Corundum is a very hard mineral (hardness 9); only diamond is harder. Corundum is called ruby or sapphire, depending on the color (which depends on which metallic oxides are present). In its rare pure form, corundum is colorless and called white sapphire. Rubies contain chromic oxide, blue sapphires contain titanium, yellow sapphires contain ferric oxide. Other impure forms are opaque. Corundum stones can produce beautiful asterisms. The word corundum comes from the Tamil word for ruby. Corundum has a specific gravity of 3.96-4.01.
Highly fashionable clothing and jewelry created by leading designers.
A crimp bead is a soft, metal bead through which string (for a bracelet or necklace) is threaded; the crimp bead can be squeezed shut with a pliers to secure the end loops of the threading material fasteners onto the clasps.
The crown is the upper part of a gemstone.
Crown glass is glass that contains no lead oxide. Some fake rhinestones are made from crown glass.
Crystal is high-quality glass containing at least 10% lead oxide. Lead added to the melt produces very clear glass resembling rock crystal. The process of making lead crystal was discovered by the English glassmaker George Ravenscroft in 1676. Crystal is colored by adding various metallic oxides to the melt.
A crystal is a solid whose atoms form a very regular structure. Some crystals include quartz, diamond, and emerald.
Crystal habit is the crystal form that a particular crystal has. The most common crystal habits:
Prismatic – elongated with parallel sides, like emerald, tourmaline
Tabular – short and flat (table-like), like morganite
Ocatahedral – eight faces, like diamond
Dodecahedral – 12 faces, like garnet
Acicular – needle-shaped, like rutilated quartz
Platy – occurring in very thin plates, like hematite
Crystals are divided into seven crystal systems, according to their optical properties (how light bends within the crystal), plane of symmetry, axis of symmetry, center of symmetry, crystallographic axis. Within each of the systems, the crystals can mineralize into different crystal habits (form). The seven crystal systems are: cubic systems, tetragonal systems, hexagonal systems, trigonal systems, orthorhombic systems, monoclinic systems, and triclinic systems.
Cubic zirconium (also known as cubic zirconia or cz) is an inexpensive, lab-produced gemstone that resembles a diamond. Cubic zirconia was developed in 1977.
A cuff bracelet is a stiff, relatively wide bracelet. The cubic zirconia , hinged cuff seen on catalog from Forever Collection designed by the jewelry designer Lisa Hsieh.
Cufflinks are men’s jewelry that close the buttonholes of the cuff of a long-sleeved shirt. Some cufflinks are basically two button-like objects connected by a chain; the bottons go through the cufff’s buttonholes. Another type of cufflink has a decorative button attached to a stick whose end swivels out to form a T-shape that goes through the buttonhole. Cufflinks were first worn in the 1800’s.
A culet is the bottom point of a gemstone or a small facet that is ground at the base of a brilliant-cut gemstone. The culet prevents splintering of the stone. Modern stones rarely have a faceted culet.
The Cullinan diamond (also called the Star of Africa) is the largest diamond yet found, weighing 3,106 carats (roughly 1.3 pounds) in its rough form. It was mined at the Premier Mine in South Africa in 1905. This enormous gem was named for the chairman of the company that owned the mine. It was given to King Edward VII of England for his birthday in 1907. The diamond was cut (by Joseph J. Asscher of Amsterdam) into many stones, including the Cullinan I (530 carats, pendelique-brilliant shaped, the largest cut diamond in the world), the Cullinan II (317 carats, cushion shaped), Cullinan III (94 carats, pendelique shaped), Cullinan IV (63 carats, square-brilliant shaped), and many other smaller stones.
Cultured pearls are pearls produced by oysters that have been surgically injected (nucleated) with bits of mussel shell. After 5-7 years, the oysters are retrieved and the pearls are harvested. This method of “manufacturing” pearls was invented in 1893 by Kokichi Mikimoto.
Cupid’s Darts is another name for rutilated quartz.
Cushion cut stones are shaped like a cushion – they have a squarish shape that is rounded on the edges. These stones usually have facets similar to those of a brilliant cut stone.
Cut beads are glass beads that have been faceted. This process makes the bead reflect and refract more light.
Common cuts include the brilliant cut, old European cut, emerald cut, radiant cut, rose cut, step cut, pendelique cut. Mixed cuts in which the style of the facets above and below the girdle are different. Other, more unusual cuts, are know as fantasy cuts (like the heart cut).
Danburite (Calcium borosilicate – CaB2Si2O8) is a clear to white silicate mineral whose orthorhombic crystals are transparent to translucent (danburite can also be yellow, greenish, or brown); it resembles topaz. It was named for the city of Danbury in Fairfield County, Connecticut, USA (where the original specimens were found in 1839). Danburite is also found in Russell, New York (USA), Charcas and San Luis Potosi (Mexico), Kyushu Island (Japan), Madagascar, Siberia, Mogok (Myanmar), Bolivia, and Uri (Switzerland). Danburite has a hardness of 7 – 7.3 and a specific gravity of 2.97 – 3.02. Its streak is white
Damascening is the inlaying of a soft metal (like silver or copper) into a hard metal (like steel). The name comes from the city of Damascus, where this process was first used.
Darya-i Nur (meaning “Sea of Light”) is one of the largest-known diamonds. It is a flawless, transparent, pink diamond from India, weighing about 175 to 195 carats. It was taken to Persia (now Iran) after Persia’s attack on Delhi, India, in l739. The Darya-i Nur is in the crown jewels of Iran, and was worn by the Shah of Iran.
Dead pawn is an item that was pawned but was never collected by the original owner.
A “dead” stone is a foil-backed rhinestone that has lost its original shininess, usually after water has damaged the foil. For example, a “dead” clear rhinestone will appear dull and off-white, greenish or yellowish.
Dead soft is a term that refers to very soft-tempered metal. Dead soft wire is the most easily bent wire. For example, copper electrical wire is dead soft.
Demantoid garnets are valuable green, very lustrous garnets with a cubic crystalline structure. They are a rare variety of andradite. Demantoid garnets have characteristic inclusions that look like horsetails. Demantoid garnets have a hardness of 6-7 and a specific gravity of 3.8 – 3.9. Demantoids were very popular in the 1800’s, but are rarely used today.
Dendritic means tree-like, having a branching pattern (like moss agate).
Denim lapis is a relatively pale, inexpensive variety of lapis lazuli that is from Chile. It is the color of denim cloth due to calcite inclusions (which whiten the stone and lower its value).
Dentelles (meaning “lace” in French) are rhinestones cut with 32 or 64 facets.
A demi parure is a matching set of jewelry, usually containing a necklace, earrings, and a pin. See parure.
A diadem is a tiara, a circular or semi-circular piece of jewelry worn on the head.
Diamante is another word for rhinestone.
Diamonds are precious, lustrous gemstones made of highly-compressed carbon. Diamonds are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 – 2.419. Colors of diamonds range from colorless, yellow, orange, brown, to almost black. Rarer colors are red, blue, green, and purple; these colors (called fancies) are quite valuable. Canary diamonds have a deep yellow color. A diamond’s value is based on the “4 C’s”: color, cut, clarity, and carat weight. A diamond’s color (saturation) is rated on an alphabetical scale ranging from D (white) to Y (yellow). “Z” diamonds are fancy, or deep-colored diamond. A diamond’s cut is designed to maximize the stone’s natural “fire”; brilliant cuts are preferred. A diamond’s clarity depends on the number and size of its flaws and inclusions (of other minerals, like quartz). Clarity is rated from FI (flawless), IF (flawless at 10x magnification), a series of V ratings (very small flaws at 10x magnification), a series of S ratings (small flaws at 10x magnification), to I1, I2, and I3 (having inclusions visible to the naked eye). A diamond’s carat weight is simple how much it weighs (a carat is about 0.2 grams or about 0.007 ounces). The largest-known gem-quality diamonds include the Cullinan (aka the Star of Africa, 530.20 carats), the Excelsior, the Great Mogul (an ancient Indian diamond which is said to have originally weighed 787.5 carats, but its location is not not known and nothing about it has been authenticated), the Darya-I Nur, the Koh-I Nur, and the Hope diamond (named for its purchaser, Henry Thomas Hope).
Not to be confused with diamond chips, these small diamonds are full cuts, containing all 58 facets, and are frequently used in fine jewelry as accent diamonds. The word melee refers the diamond’s weight, which is less than 1/5 of a carat.
Diapering is a crisscross pattern of diamond-shaped lines on a raised-dot enamel pattern.
Dichroism is the property of having more than one color, especially when viewed from different angles. Many minerals (like rubies and axinite) are naturally dichroic. This effect can be artificially caused by a thin layer of a metallic oxides that is deposited on the surface of a material. Dichroic coated glass transmits some wavelengths of light and reflecting others, giving it an opal-like appearance.
Die stamping (also known as machine-stamping) is a process in which sheet metal is cut and shaped between two dies, forming a pattern in relief. Two steel dies are used, the male die has the design in cameo (protruding); the female die has the design hollowed out. The male die is put on top of the metal, the female die is put on the underside of the metal. The press is forcefully brought down onto the dies and metal, forcing the metal into the shape of the mold. Many medallions and mass-produced jewelry findings are made this way.
Diffusion treated stones are color-enhanced (not naturally colored) stones. The diffusion process only colors the outer surface of the stone, so chipping or re-polishing will result in a loss of color. Diffusion-treated stones are already-cut stones that are heated in the presence of other compounds (like iron oxide, chromium oxide, titanium dioxide, etc.) that will infuse the extreme outer surface stone with color. Under a microscope, you can see the loss of color within each tiny scratch. Diffusion treatment can also change the stone’s refractive index. Also, if the stone is faceted, the color will appear stronger where the facets meet.
A dog collar (also known as “collier de chien”) is a type of short, multiple-strand choker-style necklace that fits tightly against the neck. Dog collars are also known as ” plaque de cou” (meaning “neck badge”) when they are fastened by a clasp in the front. Dog collars are 14″-15″ in length.
A doublet (also dublette) is a gem made from two layers in order to save expenses; the lower part of the composite stone is glass or a non-precious stone, the top is the more valuable stone. Many different types of doublets have been manufactured (including opal doublets). One common doublet contains a layer of real garnet and a layer of glass. A thin, red garnet top is glued to a colored glass bottom. A green glass bottom with a red garnet top layer produces an emerald-like stone. A diamond is enlarged by cementing it to a crystal base.
DOUBLY REFRACTIVE STONE
In doubly-refractive stones, the light entering the stone is split into two light rays, and the rays travel in different paths. These stones have more than one refractive index. Calcite, peridot, zircon, tourmaline, and titanite are doubly-refractive stones. Birefringence is another name for double refraction.
A drop cut (or briolette) is a pear-shaped cut gemstone with triangular facets on top. This type of stone makes a nice pendant.
Sometimes referred to as a “dangle earring”, this design includes any earring with hangs below the earlobe.
Druze is a layer of crystals that form within a mineral crust, like the inner cavity of a geode. Amethyst crystals are often found in a druze. The inner cavity of agate geodes are often lined with a druze of sparkling quartz crystals
A ductile substance is easily pulled or stretched into a thin wire. gold is the most ductile metal.
Dumortierite (Aluminum Boro-silicate Hydroxide) is a blue to violet silicate mineral that is used as an ornamental stone (and sometimes as a semi-precious stone in jewelry). Dumortierite quartz is a massive variety of opaque quartz that is intergrown with dumortierite crystals. Dumortierite has a hardness of 7 – 8.5 and a specific gravity of 3.3 – 3.4.
Ebonite (also called vulcanite) is a hard, moldable, polished dark colored (ranging from brown to black) early rubber. Ebonite was produced by adding sulfur to vulcanized rubber. It was used for combs, ornaments, and buttons. Ebonite is sometimes confused with gutta percha.
Ebony is a hard, dark, dense wood sometimes used in jewelry.
The Edwardian period (also known as the Belle Epoque) was the time of the reign of Edward VII of England (1901-1910). Edwardian jewelry is delicate and elegant. Edwardian designs frequently use bows and filagrees. Pearls and diamonds were also frequently used.
Eilat stone is only found in King Solomon’s copper mines on the Red Sea, near Eilat, Israel. This opaque green mineral is composed of azurite, malachite, turquoise, and chrysocolla. The hardness of this copper-based stone varies. There are many variations on its spelling, including Eliat, Elat, and Ellat.
Electroplating (also called Galvanotechnics after its inventor, Luigi Galvani) is a process in which one metal is coated with another metal using electricity. In jewelry, inexpensive metals are frequently electroplated with more expensive metals, like gold (gold plating), copper (electrocoppering), rhodium (rhodanizing), chromium (chromium plating), or silver (silver plating). The thickness of the metal coat varies. Electrogilded coating is the thinnest (less than 0.000007 inches thick); gold-cased metals have a coating thicker that 0.000007 inches.
Electrum is an amber-colored alloy of gold and silver that was used in ancient times. Electrum is also an alloy used in medieval times consisting of copper (50%), nickel (30%) and zinc (20%).
An Elie ruby is actually a pyrope garnet (and not a ruby at all).
Embossing is a method of surface decoration in which a design is raised slightly above the surface. Sheets of metal, leather, and plastic can be embossed.
Emeralds are a very hard, green precious stone (beryl, Be3Al2Si6O18, colored by chromium and some vanadium impurities). Flaws and cloudiness (called jardin) are very common in emeralds, so many emeralds are oiled, irradiated , and dyed to improve their look. Synthetic emeralds (developed by Carroll Chatham in the 1930’s) have fewer imperfections and are very hard to distinguish from natural emeralds. Emeralds belong the beryl group of stones which also includes aquamarines, morganite, and chrysoberyl). Emeralds have a hardness of 7-8 and a specific gravity of 2.6 – 2.8. Emerald (and all forms of beryl) have large, perfect, six-sided crystals. Emeralds were long thought to have healing powers, especially for eyesight. During the renaissance, emeralds were used as a test for friendship among the aristocracy; an emerald given to a friend would remain perfect as long as the friendship endured.
Emerald cut stones have a girdle that is rectangular with truncated corners. Emerald cuts are frequently used on emeralds and diamonds.
Enamel is a glassy substance (powdered glass with colorants) fused onto metal using heat
Engraving is a method of surface decoration in which a design is etched into the surface with a sharp tool.
By definition this term simply means “previously owned,” although many people today have confused the term to be interchangeable with antique jewelry.
An etched finish on a metal’s surface reduces the metal’s reflectivity. It is done by using harsh chemicals to eat into the surface or by cutting into the surface using a sharp tool.
Traditionally, this term refers to a millenniums old ring design wherein the band has been set with a continuous row of gemstones. Today it is most frequently given to mark an anniversary or the birth of a child, though many have begun exchanging the rings as bridal bands.
Ancient Etruscan jewelry has intricate and beautiful designs; most is made of gold. The Etruscans employed a lot of delicate granulation (n which tiny beads of gold are soldered to the surface to form a pattern) and openwork filagree (in which filagree patterns are not applied over sheet metal). The Etruscans lived in Northern Italy for hundreds of years beginning in the late 8th century B.C.
The European cut (also known as the old European cut) is an old, round diamond cut that is similar to but less bright than the newer brilliant cut. The European cut has a very small table and heavy crown.
An eyepin is a thin wire with a loop at one end; it is used for linking beads together.
The Excelsior is the second- or third largest diamond (depending on whether or not the Braganza diamond was actually a diamond). This irregular-shaped blue-white diamond was roughly 995 carats. It was found in l893 by a worker at the De Beers mine at Jagersfontein, Orange Free State, South Africa. The Excelsior diamond was cut in 1904 by I.J. Asscher and Company of Amsterdam into 21 stones, including a 69.80-carat marquise, an 18-carat marquise stone (which was displayed at the l939 World’s Fair by the De Beers company), and many other stones.
The legendary jeweler to the Tsars, this talented Russian became most famous for his world-renowned jewelled eggs. Numbering 56 in total, of which 44 remain, these prized enameled eggs were created as Easter gifts for the Russian court beginning in 1884, each one containing a precious surprise. Fabergé creations are famous for their meticulous craftsmanship and mind-boggling detail.
The polished surface/plane on a diamond or gemstone.
Faceting is the cutting and polishing of the surface of a stone.
Fancy diamonds are rare diamonds that are red, blue, green, or purple; these diamonds are quite valuable. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 – 2.419.
Fancy cut stones are cut in unusual ways. Some fancy cuts include the heart, fan, rivoli, trapezium, cathedral window, half-moon (lunette), kite, and triangle.
The fantasy cut is a new way of faceting stones that uses freeform angles – virtually anything goes.
Faux means false. A faux gem is an imitation.
Fashion jewelry is another name for costume jewelry.
A feather is an internal flaw (also called an inclusion) in a gemstone that can start at the surface of the stone and extend deep inside. Feathers can either ruin a stone (by making it fragile and/or changing the color), or add to its beauty.
A fede ring is one that depicts two hands clasped together
Feldspars are a family of minerals that include moonstone (adularia), amazonite, sunstone, and labradorite.
A fetish is a charm, amulet, pendant or other decoration associated with magical properties; it often represents an animal or person.
A fibula is a brooch (pin) that looks a bit like a safety pin. Fibulas have been used since ancient times to secure clothing.
Figural jewelry is disigned to look like real objects. Common subjects are the human body, animals (especially butterflies, dogs, cat, birds, and shells), flowers, leaves, and everyday objects (like baskets and fans).
Filigree is gold or silver wire that have been twisted into patterns and soldered into place. Openwork filigree is not soldered onto a sheet of metal and is difficult to make. Imitation filigree is made of stamped metal.
Findings are the parts that jewelers use in making jewelry. For example, clasps, hooks, pin backs, jump rings, and earring backs are findings.
Fineness is the proportion of silver or gold in a metal alloy. Fineness is usually expressed in parts per thousand. For example, the fineness of sterling silver is 925.
FINGER RING SIZE
To size a finger for a ring, a finger-ring gauge is used. The rings are marked with their size and the person determines which one fits well. Another, less accurate method is a cardboard card with cut-out holes marked with the ring sizes. To determine the ring size of a finger using the circumference of the finger, or to determine the size of a ring given its diameter.
The texture or polish on any piece of jewelry.
A stone’s fire is the streaks of brilliant color within it. Good quality opals have a lot of fire.
Fire opals are a type of opal that is firey orange to red in color (but have no opalescence). These opals are rarely transparent – they are usually milky. Opal is a mineral composed of silica (and some water) and is a species of quartz. Many opals have a high water content – they can dry out and crack if they are not cared for well (opals should be stored in damp cotton wool). Opals have a hardness of 5.5 to 6.5 and a specific gravity of 1.98-2.50. Fire opals are found in Western Australia, Mexico, Brazil, Guatemals, and Honduras.
Firestone is an imitation iridescent rainbow quartz. It is made by heating rock crystal until it crazes; it is then put into dye as it cools.
A flaw is a an imperfection in a gemstone. Flaws include: cracks, inclusions of other minerals or liquid-filled cavities. A flawless stone is called “clean.” Flaws can greatly reduce the value of a stone, but in some cases, like moss agate or rutilated quartz, the “flaws” increase the value of the stone.
An floater (or invisible) necklace looks as though the beads are simply floating on the skin; the beads or pearls are strung far apart from one another on an almost invisible string (like clear fishing line).
A Florentine finish on a metal’s surface reduces the metal’s reflectivity. It is accomplished by engraving parallel lines into the surface using a sharp tool, and then making more lines or curves at right angles (cross-hatching).
Flowering Obsidian (also called snowflake obsidian) is a volcanic glass that is usually dark (black or brownish) with white “snowflakes”. This glassy, lustrous mineral is found in lava flows, and obsidian stones can be massive. Obsidian is formed when viscous lava (from volcanos) cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35.
Fluorescence is property in which light (or other radiation) is emitted from an object. Many stones (including some diamonds) flouresce when exposed to ultraviolet light.
Fluorite is a mineral that comes in many colors, including purple, clorless, red, pink, yellow, green, blue, black, and multi-colored stones. Crystals are transparent to translucent. Fluorite is relatively soft – it has a hardness of 4 and a specific gravity of 3.0 – 3.3. The chemical formula for fluorite is CaF2. Fluorite is frequently fluorescent (various varieties fluoresce red, blue, green or yellow light). Fluorite is found all around the world. Some varieties of fluorite include: Blue John (purple with bands of white or yellow), Chlorophane (thermoluminescent – emitting bright green light when heated), Yttrofluorite (yttrium replaces some of the calcium – formula = [Ca,Y]F2), Yttrocerite (cerium and yttrium replaces some of the calcium in its structure – formula = [Ca,Ce,Y]F2, Antozonite (contains uncombined fluorine ions – when fractured or cleaved, it gives off an odd odor).
A fob is a short chain or ribbon that attaches to a pocketwatch; it frequently had a decorative medallion or other ornament attached to one end. Fobs were worn hanging from a pocket. Fob is also the word for the small pocket in trousers that held a pocket watch. The word fob is also commonly used for the fob charm itself.
A foilback (or foiled stone) is a stone that has a metallic foil backing; this thin metallic backing is frequently composed of mercury and tin. Silver-colored, gold-colored, or other-colored foil is applied to the back of a stone to make the stone more reflective. Before scintillating cuts (like the brilliant cut) were invented, even precious stones were foiled to enhance their sparkle. Moisture can damage foil and make the stone “dead,” losing its brilliance. Stones are rarely foiled any more.
A fold over clasp is a jewelry fastener that is composed of a device that opens and closes with a hinge, and latches shut. It is used to attach the two ends of a necklace or bracelet.
Fool’s gold is pyrite, a shiny, metallic mineral that looks like gold, but is actually a a form of iron. Marcasite stones come from pyrite.
Fossil ivory is the tusk of the extinct Woolly Mammoth (an elephant-like animal that lived during the last Ice Ages).
Fossils are the remains of ancient animals and plants, the traces or impressions of living things from past geologic ages, or the traces of their activities. Fossils can be used to make beautiful jewelry. Fossils came in many different mineral and organic forms, including plain-looking rocks, marble-like casts of ancient animals, opals, and amber (fossilized tree resin).
A fracture is a crack in a gemstone (also called a feather).
French enamel refers to fine enamel work (like the work of Fabergé) the was first developed in France. In this technique, many thin layers of translucent colored enamel (glass paste with colorants) are applied to a metal surface. After firing the piece at temperatures of up to about 820?C, the work is polished. A final layer of clear enamel often covers the piece. Fine miniature paintings in enamel on a white-enamel ground have been produced in France since this technique was developed in 1620-1630 by the French goldsmith Jean Toutin of Chateaudun and other French goldsmiths.
“French Ivory” is synthetic (imitation) ivory. It is molded from plastics (like celluloid) and is also called Ivoride, Ivorine, and “Genuine French Ivory.”
French jet is black glass (pyrolusite glass) designed to imitate real jet. It was frequently carved.
A freshwater pearl is a pearl that was harvested from a freshwater mussel (a mollusk). These pearls are frequently shaped like crisped rice cereal, and are less valuable than oyster pearls. Biwa pearls are very good quality freshwater pearls.
Frost agate is agate with white markings (that look like frost).
“Fruit Salad” jewelry is costume jewelry that is set with colorful, molded stones. The stones are glass or plastic, and can be transparent or translucent.
Fuchsite is a deep emerald green variety of the mineral muscovite that is rich is the chromium. It has a glassy luster. Fuchsite is relatively soft; it has a hardness of 2-2.5 and a specific gravity of 2.77-2.88. The chemical formula for fuchsite is K(Al,Cr)2(AlSi3O10)(OH)2.
A full cut stone is a gemstone with 58 facets.
Furnace glass (also called furnace worked glass) is made by working (shaping) hot glass by hand (the glass was heated in a glass furnace). Long tubes of glass are drawn from molten glass, then beads are cut from the tube (and later tumbled and reheated to smooth the edges of the beads). Furnace glass beads are made in a wide variety of colors, shapes, and designs.
G (IN COLOR)
When grading diamonds “color” refers to the absence of color in a diamond. The rating scale begins at D (meaning colorless) and ends at Z (meaning having a lot of colors). Though some color can be seen when a G diamond is graded, it appears colorless when mounted, thus it is commonly used in fine jewelry.
Gablonz (Jablonec nad Nisou) is a city in the Czech Republic, in Bohemia, that is a center of jewelry making. Before World War 2, Gablonz was a center of high-quality glass-blowing, bead-making, and other costume-jewelry related products.
Gagate (popularly known as jet) is fossilized coal. It is a hard, lustrous black stone that was used in mourning jewelry during the Victorian era (especially after Queen Victoria’s husband died and she went into a long-lasting mourning, affecting fashion). Jet is frequently cabochon cut. Gagate has been mined near Whitby (on the Yorkshire coast of England) since prehistoric times. It is also found in Spain. France, Germany, and Russia, but these other sources are said to be inferior to the harder, more elastic Whitby jet. Jet/gagate has a hardness of 2.5-4 (quite soft) and a specific gravity of 1.30-1.35 (it is relatively lightweight). Jet leaves a brown streak. When burnt with a red-hot needle, jet smells like coal Black glass and plastics are often used to imitate jet (glass is much heavier and harder than jet) – jet is warm to the touch.
Gahnospinel is a rare blue spinel stone that is high in zinc and magnesium. It can only be distinguished from most spinel by its high specific gravity and high refractive index. Gahnospinel has a hardness of 8, a specific gravity of 3.97. Its chemical formula is (Mg, Zn)Al2O4.
A gallery is a strip of metal that is perforated with a decorative pattern. Open galleries can be adapted by jewelers to use as a ready-made claw setting for gemstones.
Popular during the Edwardian era, this style (which includes bows, swags, and tassels) was made famous by the house of Cartier who set the delicate design in platinum.
Garnets are any of a group of semi-precious silicate stones that range in color from red to green (garnets occur in all colors but blue). Some garnets used as gemstones include pyrope (the deep red garnet), almandine, spessartine, grossular, the iron-aluminum dark red garnet (also known as the carbuncle stone), Uvarovite (rare), and the lustrous Andradite (which includes the valuable green demantoid garnet, Topazolite , and Melanite). Red garnet is the birthstone for January. Garnet has a hardness of 6-8 and a specific gravity of 3.5 – 4.3.
Types of Garnet:
Grossular – Colorless, orange, yellow, pink, or brown
Pyrope – Colorless, pink, or red
Pyrope Almadine – Red-orange to red-purple
Almandine spessartine – Red-orange
Chrome pyrope – Orange-red
Almandine – Orange-red to purple-red
Hessonite – Yellow-orange to red
Spessartine – Yellow-orange
Topazolite – Yellow to orange-yellow
Malaia – Yellow to red-orange to brown
Andradite – Yellow-green to orange-yellow to black
Demantoid – Green to yellow green andradite
Tsavorite – Green to yellow-green
Pyrope-Spessartine – Green-yellow to purple
Color-change garnet – Blue green in sunlight; purple-red in incandescent light
Transvaal “jade” – Bright green grossular garnet
Uvarovite – Emerald green
Grape – purple
Rhodolite – Purple-red
Xalostocite – Pink grossular garnet
Gaspeite is a pale green to apple-green semi-precious gemstone that often has brown inclusions of its host rock. Gaspeite is translucent to opaque. This beautiful stone has only recently been used in jewelry, and is often set in silver. Gaspeite has a hardness of 4.5 – 5, and a specific gravity of 3.7. Gaspeite is Nickel Magnesium Iron Carbonate; its chemical formula is (Ni, Mg, Fe)CO3. This stone is found in Gaspe Peninsula, Quebec, Canada (where it was originally found and from which it derives its name) and Kambalda and Widgie Mooltha, Western Australia, Australia.
A gemstone (also called a precious stone) is a mineral that is valuable, rare and often beautiful. A few organic materials, like amber, coral and pearls are also considered gemstones.
A geode is a rock whose crystal-filled interior can be hollow or filled. The crystals that form within the mineral crust of the geode is called druze. From the outside, geodes look like rounded, but otherwise ordinary rocks.
German silver (also know as nickel silver) is an alloy consisting of mostly copper (roughly 60 percent), and approximately 20 percent nickel, about 20 percent zinc, and sometimes about 5 percent tin (then the alloy is called alpaca). There is no silver at all in German silver. This alloy was invented around 1860 in Germany as a silver substitute.
GIA stands for the Gemological Institute of America.
A gimmel ring is a double ring that was designed during the Renaissance. It consists of two or more interlocking rings. A gimmel ring symbolizes the union of two people.
The gipsy setting is a recessed setting in which the stone is sunk into the metal. There are often engraved designs around the stone (especially star patterns). This type of setting was developed in the late 1800’s and was often used for rings. The gipsy setting is also known as the “star setting.”
A girandole is a kind of earring or brooch in which three pearls, stones or pendants hang from a large stone. The central drop is usually larger than the other pendants.
The girdle is the widest perimeter of a gemstone.
Givre beads are beads made of transparent glass fused around a translucent core. Givre means frost in French.
Glass is often used in jewelry, as beads (faceted or spherical), rhinestones and as poured glass.
Glass paste (also known as pate de verre) is glass that is ground into a paste, put into a mold, and then melted. The final piece is an opaque, dense glass with a frosted surface.
Glyptography is the art of engraving gemstones, making intaglio and cameos. Stones are engraved using grindstones with powdered emory or diamond as an abrasive
Gold is a precious metal that is very soft when pure (24 Kt.). Gold is the most malleable (hammerable) and ductile (able to be made into wire) metal. Gold is alloyed (mixed with other metals, usually silver and copper) to make it less expensive and harder. The purity of gold jewelry is measured in karats. Some countries hallmark gold with a three-digit number that indicates the parts per thousand of gold. In this system, “750” means 750/1000 gold (equal to 18K); “500” means 500/1000 gold (equal to 12K). Alloyed gold comes in many colors:
Yellow Gold – 50% silver and 50% copper
White Gold – Nickel, zinc, copper, tin and manganese
Pink (rose) Gold – 90% copper and 10% silver
Green Gold – High proportion of silver or cadmium
Blue Gold – Some iron
Grey Gold – 15-20% iron
Karat – Percent Gold :
24 Kt. – 100% Gold
18 Kt. – 75% Gold
14 Kt. – 58.3% Gold
10 Kt. – 41.7% Gold
Gold dore (pronounced gold doh-ray) is a bar of semi-purified gold (e.g. bullion). After being mined, the first stage in the purification process of the gold ore produces a cast bar (gold dore) that is approximately 90% gold. The other 10% is mostly metals like silver and copper.
Gold filled (abbreviated G.F. or written as “doubl? d’or”) jewelry is made of a thin outer layer of gold atop a base metal. For example, jewelry marked 1/20 G.F. 12 Kt. is at least 1/20th gold and is layered with 12 karat gold. To be classified as gold-filled, a piece must be at least 1/20 gold by weight.
Gold-plated metal has a very thin layer of gold on the surface, usually applied by the process of electroplating. Pieces that are gold plated are often marked G.E.P., gold electroplate, gold plated, or electro-plaque d’or.
Goldstone (also known as aventurine) is a shimmering quartz stone that ranges in color from yellow to red to light green to light brown. The shimmer is caused by tiny metallic particles (mica) within the stone (not gold).
Goshenite is the pure, colorless form of beryl (Be3AlSiO6, related to emerald and aquamarine). This hard, transparent gemstone is named for the town of Goshen, Massachusetts, where it was first found. Goshenite has been found in North and South America (especially Colombia), Northern Europe, East Africa, South Africa, and the Himalayan mountains in Asia. Goshenite has a hardness of 7.5 – 8.0 and a specific gravity of 2.6 – 2.8. It is not enhanced. Goshenite is sometimes coated with a green foil to resemble an emerald.
A graduated necklace of beads or pearls has beads that go from a small size in the back of the neck and gradually increase in size to a maximum in the front of the necklace.
A grain is a unit of weight used for diamonds and natural pearls. Four grains are equal to one carat.
Granulation is a method of decorating metal with tiny metallic spheres. Tiny beads of metal are soldered to the surface to form a pattern.
Grape garnets are a rare, intense violet to purple-red garnet. Grape garnets are made up of almandite and spessartite. They have a hardness of 7-7.5 and a specific gravity of 3.8 – 3.9. Grape garnets are found in the Orissa district of northwestern India.
Green diamonds are rare, fancy diamonds and are quite valuable. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 – 2.419
Green garnets are Demantoid garnets, a valuable green, and very lustrous type of garnet. They are a rare variety of andradite. Demantoid garnets have characteristic inclusions that look like horsetails. Demantoid garnets has a hardness of 6-7 and a specific gravity of 3.8 – 3.9. Demantoids were very popular in the 1800’s, but are rarely used today.
Green gold is gold that has been alloyed with a higher percentage of silver than copper.
Green rouge is chromium dioxide, which is used to polish precious metals, giving them a luster.
Greenstone is another name for nephrite, a semi-precious stone and a variety of jade. Nephrite is slightly softer that jadeite and is often veined; it is used in carvings, for making beautiful bowls and vases.
Grelots are small beads that have an elongated, pendant shape.
Grey gold is gold that has been alloyed with 15-20% iron.
Griqualandite is tiger’s eye from Griqualand, South Africa. It is a yellowish-brown to reddish-brown gemstone that has a silky luster. This gemstone has bands of yellow and brown; when viewed from the opposite direction, the colors are reversed. Tiger’s eye is usually highly polished and set as a cabochon (or cut as a bead) to display the stone’s chatoyancy (light reflected in thin bands within the stone). Tiger’s eye is a type of chatoyant quartz with fibrous inclusions (especially crocidolite). This stone is sometimes heat-treated. Tiger’s eye has a hardness of 7.0.
Grossular garnet is a type of garnet, calcium-aluminum silicate. Hessionite is a transparent brown, yellow, orange, or honey-colored variety of grossular garnet often used in jewelry. The yellow variety is called cinnamon stone, hyacinth or jacinth. Transvaal “jade” is a type of green to gray grossular garnet from South Africa. Pink grossular garnets varieties include landerite, rosolite, andXalostocite. Tsavorite is an emerald-green grossular garnet. Grossular garnet has a hardness of 6-7.5 and a specific gravity of 3.6.
Guilloche is a type of enameling in which translucent enamel (fused glass) is applied over a metal surface that has been engraved. The Czech guilloche pin above is studded with marcasites.
Gunmetal is a metal alloy that is composed of 90 percent copper and 10 percent tin.
Gutta percha is a resin from the Isonandra Gutta tree. Jewelry was made from gutta percha in the mid-1800’s. Gutta percha was also used to insulate electrical cables. The Gutta percha company was founded by Dr. Montgomerie in 1845 and was in business until 1930.
A gypsy ring (also spelled gipsy) is a ring with a recessed stone or stones. Also known as “star setting.”
H-I (IN COLOR)
When grading diamonds “color” refers to the absence of color in a diamond. The rating scale begins at D (meaning colorless) and ends at Z (meaning having a lot of colors). Though some color can be seen when an H-I diamond is graded, it appears colorless when mounted, thus it is commonly used in fine jewelry.
A hallmark is an official mark (or a series of marks) made in metal that indicates the fineness of the metal and the manufacturer’s mark. For example, a hallmark of 925 indicates 925 parts of gold per 1000 weight. Other hallmarks indicate the maker of the piece and sometimes the year of manufacture. In many countries (like Britain) it is illegal to hallmark metal incorrectly; some countries are notoriously lax in their enforcement of hallmark honesty.
Hammered metals have been formed, shaped, or decorated by a metalworker’s hammer. The surface of hammered metal is covered with crater-like depressions made by a hammer. Many hammered metals are used in jewelry including gold, silver, brass, aluminum, etc.
A substance’s hardness is how resistant it is to being scratched. Hardness is measured using the Mohs Scale of Hardness. In the Mohs scale, one substance is harder than another if it can scratch it. For example, a diamond will scratch garnet, but not the other way around, so a diamond is harder than garnet.
Hawk’s eye is a green, grey or blue variety of quartz that has parallel, fibrous inclusions of crocidolite that give it a greenish cat’s eye effect (chatoyancy). This mineral has a silky luster. It looks a lot like Tiger’s Eye and often occurs with it in the same rock, but the internal structure is different.
Heat treatment is the heating of stones to a high temperature in order to enhance the color or clarity. For example, blue-green aquamarine becomes blue with heat treatment and brown zircon becomes blue or clear. chromium .02%, and zinc .02%; the remaining 0.16 percent is sulfur, chlorine, and water.
Heishi (pronounced he-she) is jewelry made from disk-shaped beads of shell (or turquoise, lapis lazuli, and other stones). Each bead begins as a tiny flat piece of shell (or stone). A tiny stringing hole is drilled through the fragment. Many of these jagged pieces are strung together tightly on a wire and are then sanded into evenness using a fine-grained sandstone and then sandpaper. The result is a very smooth strand of disk-shaped beads. This is an ancient form of bead-making developed by the Pueblos of North America.
Helenite is a manmade (not natural) green glass that is made from “rock dust” (not volcanic ash) taken from the vicinity of the Mt. St. Helens volcano in Washington state. The dust is fired to 2700 degrees F, forming glass, which is later faceted and used as a gemstone. This glass is sometimes called emerald obsidianite or Mount St. Helens obsidian (but it is not obsidian, which is a natural glass). Helenite is sold as a souvenir of the eruption of Mt. St. Helens on May 18, 1980. The composition of rock from Mt. St. Helens is: Rock from Mt. St. Helens is composed of: silicone 60.50%, aluminum 16.60%, Iron 6.02%, Calcium 5.36%, Sodium 4.18%, Manganese 2.59%, Potassium 1.20%, Titanium .90%, Phosphorus .35%, Magnesium .12%, Strontium .06%, Beryllium .04%, Copper .03%, Lead .03%, Zirconium .02%, Chromium .02%, and Zinc .02%; the remaining 0.16 percent is sulfur, chlorine, and water.
Heliotrope (commonly known as bloodstone) is an inexpensive type of chalcedony that is green with red highlights (caused by iron oxide). Heliotrope is porous and relatively soft.
Hemalyke is a synthetic hematite that is made by grinding up hematite, adding a binder (glue) and then press-molding it. The stone is sometimes faceted. Hemalyke looks very much like natural hematite – it is hard to them apart.
Hematite (sometimes spelled hematite, and also known as kidney ore) is a lustrous, opaque, blue-black to silvery gray mineral often used in jewelry. Hematite is iron oxide (Fe2O3). Hematite has a hardness of 6.5 and a specific gravity of 4.95 to 5.16. When powdered, hematite is red; when rubbed on a hard stone, it leaves a red streak. Hematite was often used as seal stones, cut as intaglio. It is also used as beads and is faceted, carved or cut as a cabochon for use as a gemstone. The ancient Egyptians carved hematite into scarabs. Hematite is found in England, Mexico, Australia, Brazil, and the Lake Superior region of North America.
Herkimer diamonds are clear, lustrous, doubly terminated crystals of quartz – they are not true diamonds. These brilliant stones are also called “Middleville Diamonds” or “Little Falls Diamonds.” Herkimer diamonds have a hardness of 7. This stone is found in Middleville and Little Falls, Herkimer County, New York, USA.
Hessonite (also called “cinnamon stone”) is a cinnamon-brown to orange gemstone variety of grossular garnet. Hessonite’s formula is Ca3Al2Si3O12; manganese that gives it its characteristic brown color. This transparent stone has a hardness of 6.5 – 7 and a specific gravity of 3.6. Hessonite is found in Sri Lanka, Brazil, Madagascar, Canada, and California, USA. This stone is not enhanced
HOOK AND EYE CLASP
A hook and eye clasp is a simple and ancient jewelry fastener that is composed of a hook and a circular piece that the hook can latch onto. It is used to attach the two ends of a necklace or bracelet.
This famous diamond is named after Lord Henry Philip Hope who bought the diamond from a London merchant in 1830. Weighing 45.52 carats and displaying 60 plus facets, the diamond possesses a unique deep blue color. It now resides in the Smithsonian Institution after a dubious history of bringing tragedy to its previous owners.
Howlite is a soft, white to gray mineral that takes dye very easily, and can be dyed to imitate turquoise very well (and is sometimes unscrupulously sold as turquoise). Howlite was named for its discoverer, Henry How, a Nova Scotia geologist.
Hyacinth is a semi-precious stone that is also known as jacinth. it is a lustrous orange-yellow, orange-red, or yellow-brown type of zircon. Hyacinth has a hardness of 7.5 and a specific gravity of 4.65. Sometimes, topaz and grossular garnet of this color is also referred to as hyacinth (this can be very confusing). Hyacinth is mined in Sri Lanka. Even more confusing is the origin of the name, which comes from the Greek hyakinthos, which refers to a blue gemstone.
Hyacinth opal (also known as girasol) is a yellow or orange type of precious opal. In this opal, the play of colors seems to come from within the stone, like a floating light and seems to follow the light source.
An important and enduring symbol, often holding religious meaning.
Imperial jade is another name for emerald jade. It is a fine emerald-green color.
Imperial topaz is golden orange-yellow topaz; it is the most valuable type of topaz.
IMPERIAL MEXICAN JADE
Imperial Mexican jade is not jade at all; it is calcite that has been dyed green.
Inca emerald is an emerald that is mined in Equador.
An inclusion is a particle of foreign matter contained within a mineral. Inclusions can be solid, liquid, or gaseous. Many inclusions decrease the value of a stone, but some, like rutile forming asterisms in star sapphires and needles in rutilated quartz and tourmalinated quartz, are prized.
Indian agate is another term for moss agate.
Indicolite is a green to a blue-green variety of tourmaline.
An inlay is a piece of material (often stone or glass) that is partially embedded in another material (usually metal) such that the two materials make a level surface.
Intaglio is a method of decoration in which a design is cut into the surface. Signet rings are frequently decorated with intaglio, as seal.
Intergrown crystals occur when two mineral crystals grow together and become one.
Inverall sapphires are a type of sapphire from Inverall, New South Wales.
An investment compound is a refractory material (it can withstand extreme heat) which is slightly porous (so that gases from molten metal can escape) and can be formed into a mold (which will be used in metal casting). An example of an investment compound is plaster of paris mixed with silica, boric acid, and graphite.
An invisible (or floater) necklace looks as though the beads are simply floating on the skin; the beads or pearls are strung far apart from one another on an almost invisible string (like clear fishing line).
Iolite, also known as an water sapphire, is a transparent, violet-blue, light blue, or yellow-gray mineral. Iolite is pleochroic; a single stone will show many colors (in the case of Iolite, violet-blue, light blue, and yellow-gray). Iolite is not rare and has a hardness of 7 – 7.5. Iolite is found in Sri Lanka, India, Madagascar, and Burma.
IPB is an abbreviation for Ionized Plated Black.
IPG is an abbreviation for Ionized Plated Gold.
An iridescent object displays many lustrous, changing colors. Iridescence is caused by the reflection of light from the jewel.
Iridium is a metal related to platinum. Iridium and platinum are frequently alloyed together since the iridium increases the workability of the platinum. Iridium is also used for the points of gold-nibbed pens.
Irradiated diamonds are diamonds that have been exposed to radiation. This changes the diamond’s color (as the radiation changes the crystalline structure of the diamond). The change in the diamond is permanent. Older radiation treatments involving exposing the stone to radium; newer treatments bombard the stone with atomic particles in a cyclotron (which accelerates protons, neutrons, or alpha-partices to high speeds). The irradiated stones take on a greenish or an aquamarine hue. Irradiations of diamonds was first done in 1904 by Sir William Crookes, who exposed diamonds to radium, giving them a permanent greenish color; his diamonds are still slightly radioactive (at the level of a radium-painted watch). Newer irradiation techniques bombard the crystal with atomic particles in a cyclotron, and then the stone is heated to about 800 degrees Centigrade, producing a stone with very little radioactivity and a permanent color change.
Irradiation is the act of being exposed to radiation. Many stones (like kunzite) are irradiated in order to enhance their color. Being irradiated changes the crystal structure of the mineral by moving electrons. Irradiation techniques bombard the crystal with high-energy radiation (like gamma rays), producing a stone with very little radioactivity and a change of color. Some color changes caused by Irradiation are permanent, others are unstable and are reversed by heating or exposure to sunlight. For example, colorless topaz changes to a cinnamon brown color after being irradiated with cobalt-60 radiation, but the color fades as the stone is exposed to sunlight. A new method of irradiation changes clear topaz to a brilliant, non-fading blue.
Italian lapis is not lapis; it is actually blue-dyed jasper from Italy.
Ivory is elephant tusks (the large, upper incisor teeth), which used to be carved into beautiful jewelry, trinkets, and piano keys. The finest ivory is the white African elephant ivory; Asian elephant ivory is yellower. Ivory has a complex characteristic grain which helps distinguish it from imitations. Using ivory is now banned since elephants are in danger of going extinct. Another tusk-like material is often substituted for ivory, including walrus tusks, whale teeth, hippopotamus teeth, animal bone, palm seed, and more recently, plastics. Vegetable ivory comes from the inner seed of the South American ivory palm and was used for small items, like dice. Synthetic ivory is made from plastics (like celluloid) and is called “French Ivory,” Ivoride, Ivorine, or “Genuine French Ivory.”
Jacinth is a semi-precious stone that is also known as hyacinth. it is a lustrous orange-yellow, orange-red, or yellow-brown type of zircon. Hyacinth has a hardness of 7.5 and a specific gravity of 4.65. Sometimes, topaz and grossular garnet of this color are also referred to as hyacinth (this can be very confusing). Hyacinth is mined in Sri Lanka. Even more confusing is the origin of the name, which comes from the Greek hyakinthos, which refers to blue gemstone.
Jade is a semi-precious stone that ranges in color from green to white to lilac to brown to almost black. Translucent jade is more highly valued than opaque jade. Jade is often cabochon set; stones with imperfections are often carved (the imperfections are simply carved away). Two different minerals are known as jade: jadeite and nephrite. Jadeite is the harder of the two; it is usually used in jewelry production. Nephrite is slightly softer and is often veined; it is used in carvings, for making beautiful bowls and vases. The Chinese have prized jade for thousands of years and regarded it as having medicinal properties when worn or ingested as a powder. Natural jadeite is called Type A or Grade A jade (waxing or wax dipping is allowed). Jadeite that had been bleached and then treated with polymers (plastic) or waxes is called Type B or Grade B jade (it is less durable than natural jade). Jadeite that had been dyed is called Type C or Grade C jade (the color is less durable than that of natural jade). Jadeite that has been both dyed and impregnated with polymers is called Type B+C or Grade B+C.
Jade glass is translucent green glass that is designed to imitate jade
Jadeite is the harder of the two varieties of jade. Jadeite is harder (compared to nephrite) and is usually used in jewelry production.
JANETY, MARC ETIENNE
The royal jeweler of King Louis XVI, Janety was commissioned to create several platinum pieces for the French monarch. The only piece known to remain is a glass-lined platinum sugar bowl dated 1786 which now finds it home in the metropolitan Museum of Art in New York City. Janety fled Paris during the French revolution only to be recalled in 1795 to fashion from platinum the standard lengths and weights for the newly established metric system.
A Japanned finish in jewelry is when metal is finished with a lustrous, black lacquer.
Jasper is a common, opaque, semi-precious stone that is found in many colors, including white, brown, yellow, red, and green. Jasper is found all over the world; it is often striped, speckled, and multi-colored. Jasper has been used for intaglio carvings. Jasper is a type of quartz belonging to the chalcedony family. It is often sealed with petroleum products. Jasper is sometimes dyed to resemble lapis lazuli and misleadingly called “Swiss lapis.” Jasper has a hardness of 6.5 to 7.0.
Jasperine refers to any type of banded jasper.
Jasperized wood (also called xyloid jasper) is petrified wood. It is wood that has fossilized – all the original chemicals have been replaced with minerals, making a stone-like replica of the original wood.
Georg Jensen (1866-1935) was a Danish silversmith, ceramic artist, and sculptor. Jensen’s modern-style silver jewelry is often adorned with semi-precious stones and is avidly collected. Jensen’s workshop grew to have branches in Australia, New York, USA, and Toronto, Canada.
Jet (also known as gagate) is fossilized coal. It is a hard, lightweight lustrous black stone that was used in mourning jewelry during the Victorian era (especially after Queen Victoria’s husband died in 1861 and she went into long period of mourning, greatly affecting jewelry fashion). Jet is frequently cabochon cut. Most jet is from Whitby, England; jet has been mined near Whitby (on the Yorkshire coast of England) since prehistoric times. It is also found in Spain, France, Germany, and Russia, but these other sources are said to be inferior to the harder, more elastic Whitby jet. Jet has a hardness of 2.5-4 (quite soft) and a specific gravity of 1.30-1.35 (it is relatively lightweight). Jet leaves a brown streak. When burnt with a red-hot needle, jet smells like coal. Black glass and plastics are often used to imitate jet (glass is much heavier and harder than jet) – jet is warm to the touch.
Jewelry (spelled jewellery in Britain) is articles of personal adornment, like rings, necklaces, bracelets, cuff links, and pins. Jewelry is made from metals (especially gold and silver), stones, glass, plastic, and other materials.
Job’s tears (Coix lacryma-jobi) is a wild tropical grass plant that has very hard seeds. The white seeds are used as beads in jewelry. The seeds are dried, dyed or painted, polished, drilled and then strung into necklaces and bracelets.
A jump ring is a circular metal ring with an opening. It is used to attach two other rings or links, and is then soldered or pressed shut.
Abbreviated with the letter “K”, karat refers to the purity of gold, which is often alloyed with silver, nickel, copper or other metals to improve its workability and make the soft metal more durable. This is what the following marks mean:
24K = 100% pure gold
18K =18 parts gold and 6 parts alloyed metal(s) or 75% pure gold
14K = 14 parts gold and 10 parts alloyed metal(s) or 58.5% pure gold
Karatclad is a trademark for a very thick gold electroplating process; this type of plating is about 14 times thicker than standard electroplating.
A keeper ring is a ring which is used alongside another, more valuable ring to keep it securely on the finger.
KING LOUIS XVI (1754-1793)
Reigned over France from 1774-1792. Married to the Archduchess of Austria Marie Antoinette, he sent forces to assist the American colonies during the revolutionary war. Is quoted famously as stating that platinum was the only precious metal fit for Kings.
The king cut is a modification of the brilliant cut which is used for large diamonds. This cut has 86 facets.
A knot is a flaw (a mineral inclusion) in a gemstone (usually a diamond) that is at the surface of a gem after polishing. The knot is a small raised bump on the finished gemstone.
The Koh-i-Nur (meaning “Mountain of Light”) is one of the largest-known diamonds. It was found in India and belonged to the first Indian Rajahs of Malwa (in the 1300s). The gem made its way to Persia in the 1500s (taken as a spoil of war by the Mogul Sultan Babur). At some point it was returned to Indiabut was taken by the East India Company and presented to Queen Victoria of England in 1850. Tge gem was later cut and set into a brooch and later into the State Crown of the United Kingdom. The Koh-i-Nur is part of the crown jewels of England and is kept in the Tower of London, London, England.
Kunzite is a transparent pink, light pink, or light purple gemstone that resembles roze quartz. It is a variety of the mineral spodumene. Kunzite can fade after prolonged exposure to light. Kunzite is also called “evening stone,” because of its propensity to fade in bright light. The original color of some kunzite stones can be restored or even intensified by irradiation. It is usually used as a large stone and is easily chipped; small stones of kunzite are difficult to cut. Kunzite is often used in pendants. Kunzite has a hardness of 6-7 and a specific gravity of 3.1 – 3.2. Kunzite was first found in 1902 in Pala, California, USA, and is named for the gemologist George F. Kunz. Kunzite’s chemical composition is LiAlSi2O6
Kyanite is a deep sapphire blue, green, gray, or white gemstone. The color is not always uniform; it can be blotchy or in streaks. The cystals are crystals are transparent to translucent. Kyanite has a hardness of 4.5 to 6.5; the hardness varies depending on which way it is scratched (this happens because kyanite consists of long, thin crystals). It has a specific gravity of 3.58. Kyanite is found in Brazil, Burma, Kenya, Europe, India, Australia, Kenya, and the USA. Kyanite’s chemical composition is Al2SiO5; it is composed of andalusite and sillimanite.
LAB RUBY (SAPPHIRE)
A lab ruby (or sapphire) is a synthetic (laboratory-made) stone. It has the same composition, hardness, and specific gravity as natural rubies (or sapphires) but is much less expensive than a natural stone (since they are relatively inexpensive to create in the laboratory as compared to mining gemstones). These lab-produced stones can be legally referred to as “real” stones [as opposed to “natural” (mined) stones].
Labradorite (a variety of plagioclase feldspar) is a fairly abundant grayish mineral that has brilliant flashes of color (usually green, blue or red) after it is polished (called labradorescence). The crystals are transparent to translucent. There is a darker variety of labradorite (called “black moonstone”) which has bluish inclusions. Labradorite is usually cut with a flat surface in order to highlight the flashes of color. Labradorite was originally found along the coast of Labrador about 1805; it is also found in Newfoundland, other parts of Canada, also known as spectrolite, Ukraine, the Ural mountains, and the USA. Labradorite has a hardness of 6 to 6.5 and a specific gravity of 2.70. Finnish labradorite is also known as spectrolite.
A lapidary is someone who cuts and polishes gemstones.
Lapis lazuli is a rich blue opaque, semi-precious stone that has been used in jewelry since ancient times. Ground-up lapis lazuli was once used as a pigment for oil paintings. Lapis lazuli is often dyed to deepen and improve its color. Lapis has a hardness of 5.5; it chips and scratches easily. It has a specific gravity of 2.4 to 2.9. Water can dull its sheen. Lapis lazuli contains the minerals calcite (which decreases its value), pyrite (which can increase its value), and sodalite. Swiss lapis is not Lapis lazuli at all; it is dyed jasper. Denim lapis is relatively pale, low-grade, inexpensive lapis from Chile; it is the color of denim cloth because of calcite inclusions (which whiten the color and lower the value).
Larimar is a form of pectolite (with copper) found only in a single place in the Dominican Republic. It is an opaque sky blue stone with white streaks. There are often some red to brown impurities. Larimar is usually shaped and polished (but not faceted). Larimar has a hardness of 4.5 – 6.0 and a specific gravity of 2.7 to 2.9. Larimar is not enhanced. Larimar was named for Larisa (the daughter of Miguel Mendez, a geologist who helped reintroduce this stone) and mar (the Spanish word for sea)
A lathe is a machine that turns metal, wood, etc. The material to be turned is held horizontally on the machine and rotated very quickly while the jeweler applies a sharp cutting tool to the material, removing excess material, shaping the article. Rings are sometimes turned on a lathe, but most jewelers do not use lathes.
Lava from the volcano Vesuvius near Pompeii in Italy has been used to make jewelry, especially cameos. Lava jewelry was popular in the nineteenth century.
A lavalier is a pendant with a dangling stone that hangs from a necklace. Lavaliers were named for the infamous Duchess Louise de La Valliere (1644-1710), a French woman who was a mistress of the French king Louis XIV (and was involved in many intrigues at court).
Lead crystal is a high-quality glass containing at least 10% lead oxide. Glass containing at least 24% lead oxide is called lead crystal. Glass containing at least 30% lead oxide is called full lead crystal. Lead added to the melt produces very clear glass resembling rock crystal. The process of making lead crystal was discovered by the English glassmaker George Ravenscroft in 1676. Crystal is colored by adding various metallic oxides to the melt. When cut and polished, the crystal becomes quite brilliant.
Metallic leaf is paper-thin sheets of metals. For example, gold, silver, platinum, and copper are rolled or pounded into metallic leaf which can be applied to surfaces.
LEATHER CORD JEWELRY
Jewelry strung on a thin leather cord has become popular recently. Pendants, beads, shell, feathers, and/or sharks teeth are strung on leather to make interesting necklaces and bracelets.
A lentil cut stone is a cabochon cut in which the upper and lower portions of the stone are identical.
LINDE STAR SAPPHIRE
Linde star sapphire (“Linde stars”) are synthetic star sapphires that were first made by the Linde Air Products Company in 1947 (they also developed star rubies that year). The Linde company later became a division of Union Carbide. Star sapphires are sapphires that have a six-sided asterism.
LOBSTER CLAW CLASP
A lobster claw clasp is a jewelry fastener that resembles the claw of a lobster. A tiny spring keeps the arm of this clasp closed. It is used to attach two other rings or links of a necklace or bracelet.
A locket is a pendant that can open up. Lockets can hold photos, hair, a charm, or other small, precious object.
LONDON BLUE TOPAZ
London blue topaz (Aluminum silicate fluoride hydroxide) is the darkest blue variety of topaz. Most blue topaz is silver topaz that has been irradiated and heat treated, but some stones are blue naturally. London blue topaz is found in Brazil, U.S.A., Sri Lanka, Myanmar (Burma), Russia, Australia (including Tasmania), Pakistan, Mexico, Japan, and Africa. Topaz has a hardness of 8 and a specific gravity of 3.5-3.6.
LOST WAX CASTING
Lost wax casting is a process of casting metal in which the original model is sculpted in wax. The wax is then enclosed in clay and the wax is melted out, making a hollow mold. The mold is then filled with molten metal. The clay is broken off and the cast metal remains. This method of casting has been used for at least 4,000 years.
A lozenge has a diamond shape. A lozenge cut stone is a step-cut gem with a diamond shape.
A stone’s luster is its sparkle or sheen – the way it reflects light. The luster depends on the nature of the stone’s surface reflectivity. Some types of luster include: adamantine (also called brilliant or diamondlike, like a faceted diamond), earthy (with little reflectivity- also called dull, like shale or clay), greasy (like nepheline or apatite), metallic (also known as splendent, like pyrite or marcasite), resinous (like amber), pearly (with an iridescent reflectivity, like pearls or mica), pitchy (tarry minerals that are radioactive, like uraninite), silky (with a fibrous structure, like some tiger’s eye or satin spar), vitreous (also known as glassy, like olivine, transparent quartz, or obsidian), and waxy (like halite or turquoise). A pearl’s luster is derived from its nacre.
Mabe pearls are large, hemispherical cultured pearls that grow attached to the inside shells of oysters. Mabe pearls are used in earrings, pins, and rings.
Machine stamping (also known as die-stamping) is a process in which sheet metal is cut and shaped between two dies, forming a pattern in relief. Two steel dies are used, the male die has the design in cameo (protruding); the female die has the design hollowed out. The male die is put on top of the metal, the female die is put on the underside of the metal. The press is forcefully brought down onto the dies and metal, forcing the metal into the shape of the mold. Many medallions and mass-produced jewelry findings are made this way.
Mahogany Obsidian (also called Apache tears) is brownish obsidian. This glassy, lustrous mineral is found in lava flows, and obsidian stones can be massive. Obsidian is formed when viscous lava (from volcanos) cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35. The pin above is Mahogany (brown) obsidian
Malachite is an opaque semi-precious stone with layers of deep green and light green. It is usually found in copper mines; malachite is about 57% copper. Malachite was used as jewelry thousands of years ago by the ancients Egyptians. Malachite is usually cabochon set in silver. Russian malachite carvings were done in miniature and in large scale; malachite was also inlaid in furniture. Malachite has a hardness of 4 and a specific gravity of 3.80. It is monoclinic; it has one two-fold axis of symmetry. Malachite is sometimes coated with colorless wax, oil, or hardening agents to increase its durability and enhance its appearance.
Malleable metals are easily worked with a hammer or a roller. Gold and sterling silver are very malleable metals.
The Maltese cross is a cross whose four equal-length arms get larger the farther they get from the center. The Maltese cross brooch above is by Weiss; it has red paste stones and a Japanned finish.
A mandrel is a metal rod used to coil molten glass in order to make a bead
Marcasite is a shiny, metallic semi-precious stone. It is actually iron pyrite. Marcasite is generally faceted. The Czech guilloche pin above is studded with marcasites.
Marquise cut stones have a shape like an oval with two pointed ends.
A matinee-length necklace is a single strand that is from 22 to 23 inches (56 to 58 cm) long. Matinee-length generally refers to a string of pearls that hangs to the top of the cleavage.
A textured finish produced by brushing the metal surface to produce tiny parallel lines. Today it is popularly used in platinum jewelry, titanium, stainless steel jewelry and sometimes referred to as satin finish.
Maw-sit-sit is a rare green gemstone that has dark-green to black veining; it sometimes has white spots. The stone is opaque to translucent. Maw-sit-sit has a hardness of 6.0; the specific gravity is 2.5 to 3.5. This stone is found in Maw-sit-sit, Myanmar (Burma), and is often found neat jadeite, but maw-sit-sit is not a type of jade. Maw-sit-sit was first identified in 1963 by the Swiss Gemologist Eduard Gubelin; the local called the stone maw-sit-sit, and the name was retained. Although its exact composition is still unknown, Maw-sit-sit is composed of chromite, ureyite, chrome jadeite, symplektite, chrome amphibole, and other lighter minerals.
Relating or belonging to the middle ages, roughly from 500-1450 AD.
A melee is a small diamond, under .20 carat.
Memory wire is a tough, stiff wire that retains its shape. It is often used for necklaces and bracelets.
Mica is a soft, lightweight, transparent mineral that cleaves into thin, elastic sheets (it has a single perfect cleavage direction). It is used for lampshades and electrical insulators. There are about 30 different types of micas, ranging in color from yellow to green to gray to violet to white to brown. Mica has a hardness of 2.5 and a specific density of about 3. Tiny mica particles give the shimmer to aventurine (goldstone).
Microcrystalline is a type of mineral structure in which the crystals are so small that they can only be seen using a microscope.
Micromosaics are pictures or decorations that are made out of extremely small pieces (tiles) of stone, glass or other materials. Italian micromosaics were common souvenirs. Older examples are much more intricate, have smaller mosaic tiles, and generally have better workmanship.
A micron is a unit of length equal to 0.001 mm (millimeter).
Milanese mesh (also known as Milanese work or Milanese chain) is an intricate mesh made from spiral wires braided together. Milanese mesh is used to make necklaces and bracelets.
MILK AND HONEY EFFECT
The milk and honey effect is one in which the apparent coloring of a stone changes (from milky to the color of honey) as the angle of the light changes. When a light is shined on the stone, one side of the stone is the color of milk and the other is the color of honey. When the light changes direction, the color effect also shifts. Cat’s-eye chrysoberyl can exhibit this milk and honey phenomenon.
Millefiori (meaning “thousand flowers” in Italian) is glass that is formed from multiple canes of colored glass that are fused together and cut crosswise. Millefiori glass can also be made into beads.
A millegrain (or millegrain setting) is a setting in which the stone is secured by tiny beads [grains] of metal or a band of metal that is decorated with tiny beads of metal.
Milling is a process in which wood or metal is cut while it either the material or the tool is spinning. Symmetrical shapes and patterns are cut into the material.
Mine cut stones have a cushion-shaped girdle. This type of cut was popular in the late 1800’s.
A mixed cut in one in which the style of the facets above and below the girdle are different. A standard mixed cut is a brilliant cut above and step cut below.
These Indian emeralds were owned by Indian moguls (like Shah Jahan, the builder of the Taj Mahal) and were inscribed with sacred blessings.
The Mohs Scale of Hardness measures a substance’s hardness, that is, how resistant it is to being scratched. In the Mohs scale, which ranges from 1 to 10, one substance is harder than another if it can scratch it. For example, a diamond (hardness = 10) will scratch garnet (hardness = 6.5-7.5), but not the other way around, so a diamond is harder than garnet. This scale was invented by Austrian mineralogist Friedrich Mohs (1773-1839).
Moissanite is a very hard mineral that was discovered by Dr. Ferdinand Henri Moissan (1852-1907), a French chemist and Nobel Prize winner (Moissan did work on synthesizing diamonds and discovered carborundum in 1891). He found tiny amounts of Moissanite in the iron meteorite that was found at Diablo Canyon (also called Meteor Crater) in Arizona, USA. Moissanite ranges in color from colorless to blue to green to yellow. Its chemical makeup is Silicon Carbide (SiC); it is also called Carborundum. Moisannite crystals are transparent to translucent. Moissanite has a hardness of 9.25 (this is almost as hard as diamond) and a specific gravity of 3.1 – 3.2. Laboratory-grown Moissanite is sold as a gemstone.
A Japanese metal-smithing technique which results in a wood-like finish. Alternating layers of thin, colored metals are laminated together. Patterns are punched in the laminate, filed away or hammered. This technique produces unique and delicate patterns.
Moldavite is a rare, glassy, translucent, dark green gemstone. Moldavite is a silica-based tektite, a mineral formed when a meteorite (a rock from space) struck the Earth’s surface and melted and fused the surrounding rock. Moldavite is only found in Bohemia (the Czech Republic) in the Ries Crater in the Moldau River valley (which it was named for). Moldavite was discovered in the late 1800’s; the meteorite from which it formed hit the Earth about 14.7 million years ago. Moldavite has a hardness of 5.5-6.6. Inclusions of gas bubbles and iron/nickel spherules are common. This natural glass has been used for jewelry, religious articles, and decorative objects since prehistoric times.
Molded cameos are cameos that are made by the molding process and not by carving the material (as traditional cameos are). Molded cameos are usually made from plastic, glass, or porcelain that is formed in a mold. Often, two colors of material are used, one for the relief pattern (often depicting a person or scene) and another for the background. The molded cameo above is a Jasperware porcelain cameo made by the Wedgewood Company.
Monoclinic minerals have a crystalline structure in which there is one two-fold axis of symmetry. Jade, Malachite and moonstone are monoclinic.
Moonstone (orthoclase) is a semi-translucent stone that is made of albite and orthoclase feldspar. It is usually whitish-blue but can be colorless, yellow, orange, gray, or even reddish. Moonstone is usually set as a cabochon. Moonstone was very popular early in the 20th century and was extensively used in Art Nouveau jewelry. Moonstone has a hardness of 6 and a specific gravity of 2.57. It is monoclinic; it has one two-fold axis of symmetry. Adularia is a common type of moonstone. Oligoclase is another type of moonstone; Labradorite and albite are rare forms.
Morganite is a transparent to translucent pink gemstone. It is a variety of beryl, Be3Al2(Si6O18) that contains some manganese (giving the stone its pink color). Morganite has a hardness of 7.5 – 8 and a specific gravity of 2.71 – 2.90. It has poor cleavage and is brittle. Morganite is often heat treated to give the stone a purer pink color (and remove any yellow spots). Morganite was named for J. Pierpoint Morgan, the American industrialist and gem collector. Morganite is found in Brazil, Madagascar, Italy, Pakistan, Mozambique, Namibia, Zimbabwe, and the USA (California, Maine, Connecticut, and North Carolina
Mosaics are pictures or decorations that are made out of small pieces (tiles) of stone, glass or other materials. Italian mosaics were common souvenirs. Older examples are much more intricate, have smaller mosaic tiles, and generally have better workmanship.
Moss agate (also called Mocha stone in Britain and the USA) is a green variety of agate. It is chalcedony that has dendritic (tree-like) inclusions of green (red or black) hornblende. The inclusions often form beautiful patterns. Moss agate has a hardness of 6.5-7 and a specific gravity of 2.6. Green moss agate is found in India and some other locations.
Mother-of-pearl is the iridescent coating on the inside of oyster shells. Mother-of-pearl is used for jewelry, buttons, and other uses.
Moukaite is a semi-precious gemstone, a variety of jasper from Australia. The color of moukaite varies from red-browns to pinks, with gold and white bands.
The metal frame or housing in which gemstones are set.
Mourning jewelry is a type of jewelry worn when one is mourning the loss of a loved one. It is often black, subdued jewelry (often made of jet or black glass and metal with a Japanned finish) or jewelry that commemorates the dead (like hair jewelry or cameos). After England’s Queen Victoria’s beloved husband (and cousin) Albert died (in 1861), she went into an extended period of mourning. During these years, she wore black clothing and mourning jewelry. English fashion was greatly influenced by this, and mourning jewelry, especially jet, became quite fashionable.
Mya yay is the Burmese (Myanmar) name for the highest quality translucent jadeite.
Mystic fire (also called mystic topaz or rainbow topaz) is topaz that has been color enhanced by coating it with a fine layer of metal atoms (in a process called vacuum deposition). This stone has red, green, violet, and blue streaks. Mystic fire has a hardness of 8.
Nacre is a usually whitish crystalline substance which oysters, mussels, snails, and other mollusks secrete around a foreign object (like a tiny stone) that has made its way into their shell. As layers of nacre coat the intruder, a pearl is formed over a period of many years.
A natural pearl (also called a genuine pearl) is a pearl that was produced in an oyster, freshwater mussel or other mollusks as a reaction to a tiny invading object that happened to be caught inside its shell.
A navette is a gemstone which is cut as a marquise.
Necessaire is another word for etui, a tiny, decorative, cylindrical-shaped case that was often carried on a chatelaine. The necessaire/etui was used to carry small “necessary” items like pencils and scissors. The etui was first used in the 1720’s.
A necklace is a piece of jewelry worn around the neck. Necklaces of pearls of different lengths have different names: A choker is 14″ to 16″ long; a princess necklace is 18″ long; a matinee necklace is 22″ to 23″ long; opera is 30″ to 35″ long; a rope is over 40 ” long.
Nepal diamond is a huge flawless, pendeloque diamond that probably came from the Golconda mines in India. The Nepal diamond weighs 80 carats. It was originally owned by the Nepalese government but is now owned by Harry Winston, an American jeweler.
Nephrite is a semi-precious stone, a variety of jade (sometimes called greenstone). Two different minerals are known as jade, jadeite, and nephrite. Nephrite is slightly softer than jadeite and is often veined; it is used in carvings and for making beautiful bowls and vases.
Nevada diamond is a misleading term for artificially-colored obsidian (a semi-precious stone) – it is not a true diamond
Hard, malleable, and resistant to corrosion, this white metal is malleable and often mixed with precious metals such as gold and silver.
Nickel silver (also known as German silver) is an alloy consisting of mostly copper (roughly 60 percent), and approximately 20 percent nickel, about 20 percent zinc, and sometimes about 5 percent tin (then the alloy is called alpaca). There is no silver at all in German/nickel silver. This alloy was invented around 1860 in Germany as a silver substitute.
Niello is an ancient technique in which an engraved design in metal is filled with powdered niello alloy (a black/dark gray metal alloy composed of silver, copper, lead, and sulfur). The niello alloy is melted (the entire metal piece is heated in a kiln) and it fuses with the underlying metal. The object is then polished – the result is an enamel-like effect. Niello has been made at least since the time of ancient Rome. In older pieces, the niello alloy fills an engraved design in metal. In newer pieces, the niello forms the background – the niello alloy is simply “painted” onto the metal (this process is simpler, cheaper, and less durable).
Night emerald is a misleading term for peridot (a semi-precious stone) – it is not a true emerald.
The Nizam diamond was a huge Indian diamond that may have weighed from 340 to 440 carats uncut. After being cut into an elongated, convex shape with irregular facets, it was 277 carats. This diamond was owned by the Nizams of Hyderabad in the 1830’s. This diamond was “lost” or broken up during a battle.
The noble metals are gold, platinum, and silver. These are metals that are relatively impervious to chemical action.
Obsidian (also called Apache tears) is a volcanic glass that is usually black but is occasionally red, brown, gray, green (rare), dark with “snowflakes,” or even clear. This glassy, lustrous mineral is found in lava flows, and obsidian stones can be massive. Obsidian is formed when viscous lava (from volcanos) cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35. The pin above is Mahogany (brown) obsidian.
Oiling is a process of applying mineral oil to a stone in order to enhance it and mask inclusions, make them more transparent, and darken their color. Emeralds are frequently oiled to mask their many inclusions.
OLD MINE CUT
Old mine cut is a term that refers to a brilliant cut in which the stone is cushion-shaped and has a high crown (the upper part of a gemstone).
OLD ROCK TURQUOISE
Old rock turquoise is an old Persian (Iranian) turquoise term for very high-quality turquoise (sky blue, veinless turquoise that retains its color).
Olive is a term that refers to a bead that is olive shaped (elongated). This term is mostly used in the USA.
Onyx is a semi-precious stone that is black and white, generally arranged in layers. It is a form of agate with parallel banding. This structure lends itself to cameo making. Onyx is a species of chalcedony (microcrystalline quartz).
Opals are semi-precious stones that are luminous and iridescent, frequently with inclusions of many colors (“fire”). Opal is a mineral composed of noncrystalline (amorphous) silica (and some water) and is a species of quartz. There are three major types of opals: common opal, opalescent precious opal (white or black, with a rainbow-like iridescence caused by tiny crystals of cristobalite), and fire opal (a milky stone that is firey orange to red in color with no opalescence). Contra luz opals are transparent opals that show a brilliant play of iridescence only when light shines through the stone. Many opals have a high water content – they can dry out and crack if they are not cared for well (opals should be stored in damp cotton wool). Opals have a hardness of 5.5 to 6.5 and a specific gravity of 1.98-2.50. Opals are found in many places worldwide, but Australia has a tremendous variety of beautiful opals.
An opal doublet is a manufactured stone that is composed of two thin layers that are glued together. A thin layer of opal is glued on top of another mineral (usually a black onyx or ironstone, which enhances the stone’s color), producing a stone that is less expensive than a solid opal. Doublets must be cleaned very carefully
Opalescence is a milky white/blue type of iridescence.
Opal glass is a milky white glass that mimics opals.
An opal triplet is a manufactured stone that is composed of three thin layers that are glued together. A thin layer of opal is sandwiched between a layer of clear quartz and a layer of either obsidian or ironstone. The clear quartz is the top layer, making the gem harder (and less susceptible to scratches). An opal triplet is an opal doublet with a quartz layer on top. Triplets must be cleaned very carefully.
Opaque means blocking the passage of light (as opposed to translucent or transparent).
An open-ended necklace has no clasp; it is worn by tying the ends together around the neck. Open-ended necklaces usually have ornaments, like beads or tassels, at the ends.
An opera-length necklace is a single strand that is from 30 to 35 inches (60 to 90 cm) long. Opera-length generally refers to a string of pearls that hangs to the breastbone.
The operculum is part of many shelled animals – it is the calcified, disc-shaped “trap door” that opens and closes to protect the animal inside its shell. The operculum from a species of sea snail called the Turban Shell (Turbo petholatus, found in the South Seas north of Australia) is eye-like with a natural cabochon shape and is used in jewelry. This jewelry was popular in Victorian Era Britain. Operculum is also called Pacific Cat’s-eye.
Ormolu (meaning “ground gold” in French) is an alloy of the metals copper, tin, and zinc that is used to imitate gold. Ormolu can also be cast bronze or brass that is plated (gilded) with a gold and mercury amalgam, giving it a gold-like look. Ormolu is used in frames, chandeliers, candlesticks, and furniture ornamentation. It was very popular in Georgian and early Victorian design. Ormulu can now also refer to any gold-like metal used as decoration. Ormolu is also called bronze d’ore or mosaic gold.
Ouro Verde (meaning “green gold” in Portuguese) is a type of quartz crystal found in Brazil. This transparent stone is always irradiated (to give it its pale, golden-green color).
Oxidation is a chemical process in which oxygen atoms bond to atoms of a material (like a metal) and electrons are transferred from the oxide material to the reduced material. Iron oxidizes when exposed to air and moisture, forming iron oxide (rust). Silver oxidizes (tarnishes, Turing the surface black) when it is exposed to hydrogen sulfide in the air (forming Ag2S, silver sulfide).
Padparadscha sapphires (also spelled padparadschah) are a rare pink-orange variety of corundum or the synthetic equivalent. These gems are mined in Sri Lanka and are usually heat treated to improve and intensify the color. The name padparadscha comes from the Sinhalese word for lotus flower. Hardness = 9, Specific Gravity = 4.
Palladium is a valuable, durable, and malleable light-gray metal used in some jewelry; it is related to platinum, but is less dense and has a lower melting point. Unlike platinum, palladium reacts when exposed to aqua regia, sulfuric, nitric, and hydrochloric acids. It also develops a tarnish when it is heated. Palladium is not a shiny as platinum. Palladium was only isolated as an element in 1802 by William Hyde Wollaston and Smithson Tennant. It was first used in jewelry in 1939 (during World War 2, platinum was used for war purposes, and was not available for jewelry making – palladium was temporarily used as a substitute for platinum). White gold is sometimes alloyed with palladium (instead of nickel), resulting in a gray-white gold. After World War 2, palladium was rarely used in jewelry making because of some difficulties in working with it. Palladium was recently discovered to be useful in engine catalytic converters, and its price skyrocketed to over $700 per ounce (it had previously been much less expensive than platinum or gold) and is no longer practical to use as jewelry.
A parure is a matching set of jewelry, usually containing a necklace, earrings, brooch and a bracelet (or two bracelets). See demi-parure.
Patina is the change of an object’s surface layer that results from aging. Exposure to the air for an extended period of time oxidizes many metals, turning copper and bronze green, and gold reddish. Artificial patinas can be applied to newer objects by using acids or electrolytes.
Pave settings are stones set very close together. The stones hide the underlying surface. In better pieces, claw settings are used; in less expensive pieces, the stones are simply glued in.
The pavilion is the lower part of a cut gemstone, below the girdle.
A pear cut gemstone (also called a drop cut) is teardrop shaped This type of cut is used for pendants, drop earrings, rings, and other pieces of jewelry.
Pearls are organic gems grown within oysters and a few other mollusks. Pearls are formed when a foreign object (like a tiny stone) has made its way into the mollusk’s shell. The mollusk secretes nacre, a lustrous substance that coats the intruding object. As thousands of layers of nacre coat the intruder, a pearl is formed; this process takes up to seven or eight years (an oyster’s useful lifespan). The most valuable pearls are perfectly symmetrical, large, naturally produced, and have a shimmering iridescence (called orient luster). There are many types of pearls, including natural pearls (made with no human interference), cultured pearls (pearls made by inserting a bit of a mother-of-pearl) into [nucleating] a living oyster or by inserting a bit of foreign tissue), baroque pearls (irregularly-shaped pearls), freshwater pearls, seed pearls (tiny pearls), Biwa pearls (a type of freshwater pearl from Lake Biwa, Japan from the freshwater mussel, Hyriopsis schlegeli), blister pearls (grown attached to the shell), black pearls (gray to black pearls), Mabe pearls (cultivated blister pearls), etc. Pearls can be gently cleaned with mild soap and water. The biggest natural pearl, known as the “Pearl of Allah” or “Pearl of Lao-tse,” weighs 14 pounds (6.4 kg).
A pendant is a hanging ornament. Necklaces, pins, and earrings often have a pendant. The Christian Dior pendant shown above is costume jewelry.
A pendelique cut in one that is lozenge-shaped. This cut is frequently used for flawed stones. Pendelique cut stones are often used as pendants.
Peridot (also known as the “evening emerald” and chrysolite) is a yellow-green semi-precious stone with an oily luster; peridot is a transparent, green form of olivine. Peridot exhibits double refraction; when you look through the stone, things appear double. For example, when looking into a faceted peridot gemstone, the number of bottom facets appears to be double the actual number of facets. Most peridots are from a volcanic island in the Red Sea, Zebergit/St. John, the “Serpent Isle.” Peridots have been found in meteorites. Peridot has a hardness of 6.5. Peridot cat’s eye also exists.
Pierced work is jewelry (or other metal work) that has patterns cut out of the metal. Pierced work is done with a piercing saw a tiny chisel, or a stamping machine (with a die as the pattern). When a saw is used, the pattern is drawn on the metal, then a small hole is drilled in each of the future holes. The saw is then used to cut out the desired areas.
A pin (also brooch) is an ornament that can be pinned to a garment.
Pinchbeck (also known as “false gold”) is an alloy of copper that looks like gold. Pinchbeck was invented by the British watchmaker Christopher Pinchbeck (1672-1732) in the early 18th century. Pinchbeck consists of 83% copper and 17% zinc. Ironically, there have been many imitations of Pinchbeck (which itself is an imitation).
Pink Topaz (Aluminum silicate fluoride hydroxide) is a very hard pink gemstone. Pink topaz is usually created by irradiating common yellow topaz. Topaz has a hardness of 8 and a specific gravity of 3.5-3.6.
PLANE OF SYMMETRY
A plane of symmetry is a plane that divides a solid into two mirror-image pieces of the solid.
Plating or electroplating (also called Galvanotechnics after its inventor, Luigi Galvani) is a process in which one metal is coated with another metal using electricity. In jewelry, inexpensive metals are frequently electroplated with more expensive metals, like gold (gold plating), copper (electrocoppering), rhodium (rhodanizing), chromium (chromium plating), or silver (silver plating). The thickness of the metal coat varies. Electrogilded coating is the thinnest (less than 0.000007 inches thick); gold-cased metals have a coating thicker than 0.000007 inches.
Platinum is a very strong, dense precious metal with a white color. Platinum jewelry is usually 90%-95% pure, is very sturdy, and holds stones well. Platinum is related to iridium. Platinum is 60% heavier than gold. Iridium and platinum are frequently alloyed together since the Iridium increases the workability of the platinum. Platinum was only discovered in the 1700’s in Russia. Platinum is abbreviated Pt. and Plat.
Pleochroism is the property of having more than two colors, especially when viewed from different angles. In pleochroic minerals, a single stone will show many colors (in the case of Iolite, violet-blue, light blue, and yellow-gray will be visible).
PLIQUE A JOUR
Plique a jour is a back-less enamel that is a bit like stained glass. In plique a jour, the enamel work is translucent (light shows through it) since the backing of the enamel is absent. Cells of enamel are surrounded by delicate wire. Plique a jour is made by shaping cloisonne wire on a thin sheet of metal (or mica). Enamel (powdered glass) is fired into the wire cells. After the enamel has melted and cooled, the backing (metal or mica) is peeled away and the translucent enamel is left suspended in a supporting framework of cloisonne wire.
A point is a hundredth of a carat or 0.002 gram.
Porous stones have tiny holes in them. These holes allow water, oils, and other substances to penetrate the stone, frequently changing their appearance over time. Many stones are porous, including turquoise.
Poured glass is a jewelry technique in which glass is suspended within a metal framework. The result is a stained-glass-like effect with translucent glass. The Trifari brooch above is made of yellow glass.
This metal group is generally defined as referring to platinum, gold, and silver, which are valued for their rarity, color, and malleability.
A precious stone (also called a gemstone) is one that is valuable and rare.
A princess cut is a square-cut stone. This fancy cut is relatively new and is also known as a Quadrillion or Squarillion cut.
A princess length necklace (usually referring to a string of pearls) is 18″ long.
A promise ring is a pre-engagement ring, usually with a relatively small stone.
A Quadrillion cut is a square-cut stone. This fancy cut is relatively new and is also known as a Princess or Squarillion cut.
Quartz is a crystalline mineral that comes in many forms, including amethyst, aventurine, citrine, opal, rock crystal, tiger’s eye, rose quartz, and many others. Rutilated quartz and tourmalinated quartz have needle-like inclusions of other minerals. Quartz has a hardness of 7.0. This common mineral is found worldwide.
Quartz druze is a layer of quartz crystals that form within a mineral crust, like the inner cavity of a geode. For example, the inner cavity of agate geodes are often lined with a druze of sparkling quartz crystals.
QUEEN VICTORIA (1819-1901)
The longest-serving British monarch, Queen Victoria reigned from 1837 until her death in 1901. During her sovereignty, England experienced many political and social reforms and a rapid expansion of the British Empire.
Quinzite opal is a red to pink type of opal. This opal is also called Quincite, Quincite Opal, and Rose Opal.
The radiant cut is a method of cutting rectangular stones so that they have the sparkle of brilliant cut round stones. The shape is a rectangle with the corners clipped off – the length: width ratio is usually from 1.5:1 to 1.75:1. This cut has from 58-70 facets; it was invented in the 1970’s. The top of the stone is emerald cut (with about 25 facets above the girdle), but the bottom of the stone has brilliant cut facets (with about 36 facets below the girdle).
Rainbow calsilica is a newly-found, multi-colored, layered stone composed of calcium and silica. This stone has been recently used for Zuni fetish carvings and in some jewelry (beads and cabochon cut stones). Rainbow calsilica was only recently found in Mexico or Northern South America (its origin remains mysterious). Some people theorize that this stone formed as a result of the runoff of mining or oil-drilling chemicals, and has only formed in the last 30 to 50 years (but this is uncertain).
Rainbow obsidian is another name for obsidian that is iridescent.
Rainbow opal is a type of precious opal that has curved bands of colors (that resemble rainbows).
Rainbow topaz (also called mystic topaz or mystic fire) is topaz that has been color enhanced by coating it with a fine layer of metal atoms (in a process called vacuum deposition). This stone has red, green, violet, and blue streaks. Mystic fire has a hardness of 8.
The Rajaratna is the biggest-known “star ruby” (a ruby that exhibits an asterism, a six-pointed star of light, cut as a cabochon). It weighs 2,475 carats.
The rati is an Indian unit of weight that is used for gemstones. A rati is equal to 0.91 carats. The rati has varied in the past (and in different regions).
The Raviratna is the biggest-known ruby. It weighs 3,600 carats.
A reconstructed stone is one that is made from pieces of smaller stones or crystals). Reconstructed stones often have telltale air bubbles. For example, “Geneva rubies” (reconstructed rubies) are made from tiny ruby crystals that have been fused together. This type of stone is no longer manufactured (except reconstructed amber, which is still made) because synthetic stones are vastly superior to reconstructed stones.
Red beryl is a rare, deep red variety of beryl. Gemstone-quality forms of this mineral are found in only one place in the world, in the Wah Wah Mountains, near Beaver, Utah, USA. Small crystals of this gem were first found in 1905 in the Thomas Range in Juab County, Utah. The mine bearing gemstone-quality red-beryl was found in the 1950’s. The biggest red beryl crystal ever found was 14mm by 34mm, weighing about 54 carats. The average faceted red beryl gemstone weighs about 0.15 carats. Red beryl has a hardness of 7 – 8, a specific gravity of 2.66-2.70, and a refractive index of 1.564-1.574.
Red diamonds are rare, fancy diamonds and are quite valuable. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 – 2.419.
When light enters a medium with a different optical density (like a gemstone), the light is bent at an angle (and also changes its speed).
The refractive index is a measure of how light is refracted in a substance (like a gemstone). In doubly-refractive stones, the light is split into two light rays when it enters the stone, and the rays travel through different paths – so these stones have more than one refractive index.
A refractometer is a device that measures the refractive index of a gemstone.
Stretching from the 15th to 17th centuries, this European period experienced rapid advancements in the Arts and Sciences. The jewelry of this period feature engraved gemstones, portrait cameos, hat badges, and finger rings, in a style heavily impacted by the Medici in Florence, Italy and the Pontiffs of Rome.
Repousse is a method of decorating sheet metal in which designs are hammered into the back of the metal. Special punches are used to form the designs, which form in relief (raised designs) on the surface of the metal.
Retro jewelry is chunky, geometric jewelry from the 1940’s. Pink gold was often used in retro pieces.
Rhinestones are highly reflective glass made to imitate gemstones. The original rhinestones were quartz stones (rock crystal) obtained from the Rhine river. These stones were cut to resemble gemstones. The best rhinestones today are made of highly reflective leaded glass which is faceted and polished. The Trifari pin above has baguette cut and round cut rhinestones.
Rhodium is a white precious metal. Rhodium is extremely expensive and is often used to plate precious and base metals, giving jewelry a hard, platinum-like sheen.
Rhodochrosite is a mineral whose color ranges from rose to pink to almost yellow or brown. Although it is very pretty, this stone is soft and brittle; it is used in jewelry and for carvings and figurines. Rhodochrosite is Manganese Carbonate; its chemical formula is MnCO3. Rhodochrosite has a hardness of 3.5 – 4.5 (glass has a hardness of 4) and a specific gravity of 3.5. Rhodochrosite is found in Argentina, Peru, Germany, Mexico, South Africa, Russia, Italy, USA (Colorado and Montana), and Romania. Rhodochrosite is not enhanced.
Rhodolite (meaning rose stone in Greek) is a purple-red to pink-red variety of garnet and is a combination of almandine and pyrope (it is sometimes called pyrope-almandine garnet). This silicate stone has a hardness of 7-7.5 and a specific gravity of 3.5 – 4.3. The formula for garnet is A3B2(SiO4)3. Rhodolite is found in the US, Zimbabwe, Kenya, and Sri Lanka (Ceylon). Rhodolite is not enhanced.
A ring is a piece of jewelry worn around the finger; rings have been worn on every finger, including the thumb. Rings have been worn through the ages, and often have significant meaning. Some rings include wedding and engagement rings (denoting commitment), signet rings (impressed with the owner’s seal), bands (made from a ribbon of metal), rings denoting group membership (like Masonic rings or college rings), devotional rings (with religious meaning), and pugilist rings (pointed rings worn by boxers to harm their opponent).
Rings are sized using a graduated cone (a mandrel) with markings denoting the ring sizes. The ring is put on the cone and its size is read where it fits snugly on the cone. To size a finger, a finger-ring gauge is used. The rings are marked with their size and the person determines which one fits well. Another, less accurate method, is a cardboard card with cut-out holes marked with the ring sizes. Sizes in the US and Europe are numerical; sizes in the UK are alphabetical. To determine the ring size of a finger using the circumference of the finger, or to determine the size of a ring given its diameter, the formulas are:
Circumference in mm = 36.107 + (2.5890*Ring Size)
Diameter in mm = 11.4931 + (0.8241*Ring Size)
Ring Size =Circumference in mm
Ring Size = 3.1416 * Diameter in mm
Circumference in mm = 36.667 + 1.2368*Ring Size(where 1=A, 2=B, etc.)
Diameter in mm = 11.6713 + [0.3937 * Ring Size(where 1=A, 2=B, etc.)]
Riverstones are smooth, rounded pebbles found in rivers and on beaches. The action of the water and other rocks on riverstones polishes them naturally. Riverstones can be used as beads/stones in jewelry.
Rocaille is jewelry whose design is based on sea life, sea shells or rocks.
Rock crystal is a transparent, crystalline mineral. Rock crystal is the purest form of quartz and a semi-precious stone.
Rolled gold is a very thin sheet of gold that is laminated to a lesser metal (usually brass). The two layers of metal are heated under pressure to fuse them together. The sheet is then rolled into a very thin sheet and then used to make jewelry or other objects. Jewelry made from rolled gold wear well over time. Rolled gold pieces are marked rolled gold plate, R.G.P., or plaque d’or lamine.
A rondelle is a small disc used as a spacer in beadwork. Some rondelles are clear crystal discs, often used between colored crystal beads. Other rondelles are encircled with chanel-set diamonds or rhinestones.
A rope is a string of pearls that is over 40 inches long.
The rose cut (also called the rosette cut) for diamonds was invented in the 17th century and its use continued until the 18th century. The rose cut has a flat base and triangular facets (usually 24). This cut has little wastage of stone but is not nearly as reflective as the brilliant cut, which was invented later.
Rose gold (also known as pink gold) is gold with a pink tinge. It has been alloyed with a mix of 90% copper and 10% silver.
ROSE DE FRANCE
Rose de France is a recent name for a very pale variety of amethyst. It is also known as lavender amethyst. Rose de France has a hardness of 7.0. This pale lilac transparent gem is found worldwide and is a type of quartz. Rose de France is sometimes heat-treated in order to lighten its color and/or to remove smokiness.
Rose quartz is a form of quartz that ranges in color from pink to deep red.
Rough stones or crystals are in their natural state, they are neither cut nor polished.
Roulz is a metal alloy that consists of about copper, nickel, and silver. Ruolz is named for the French chemist and musician Vicomte Henri de Roulz, who invented the alloy in the 1800s.
Rubellite (sometimes spelled rubelite) is a red variety of tourmaline. Rubellite is red in both incandescent and daylight and is more valuable than other varieties of red tourmaline. Rubellite has a hardness of 7-7.5 and a specific gravity of 3.02-3.25. Rubellite is sometimes treated with fillers to increase the clarity of the stone.
Rubies are precious stones and a member of the corundum family. Rubies range in color from the classic deep red to pink to purple to brown. Rubies are extremely hard; only diamonds are harder. During the Renaissance, people thought that rubies could counteract the poison. Laboratory-produced rubies were created in the 1890’s; they are difficult to distinguish from natural rubies. The biggest ruby in the word is the Raviratna, which weighs 3,600 carats. Rubies have a hardness of 9 and a specific gravity of 3.9 – 4.1. Rubies are found in Afghanistan, Australia, Brazil, Cambodia, India, Myanmar (Burma), Malagasy Republic, Malawi, Pakistan, Sri Lanka (Ceylon), Tanzania, Thailand, United States (Montana and North Carolina), and Zimbabwe (Rhodesia)
A ruby spinel (or spinel ruby) is deep red, transparent spinel (not a ruby).
Rumanite is a type of opal that is from Romania.
RUSSIAN GOLD FINISH
A Russian gold finish is a matte, antique-look finish. Miriam Haskell jewelry often has a Russian gold (plated) finish.
Rutilated quartz is a type of rock crystal which contains long, fine needles of rutile crystals (titanium dioxide). This beautiful stone is usually cut as a cabochon. It is also known as Venus’ Hair Stone.
A safety catch is a secondary closure (usually on a fine bracelet or necklace) that is used in case the primary clasp opens, preventing the loss of the jewelry. It is often a hinged, snapping loop that is permanently attached to one side of the clasp (often a box clasp), and, when the bracelet is closed, snaps onto the other side of the clasp.
A safety chain is a secondary closure (usually on a fine bracelet or watch) that is used in case the primary clasp opens, preventing the loss of the bracelet. It is usually a chain that is permanently attached to one side of the bracelet and attaches to the other side with a spring ring clasp (or other types of clasp). On the Miriam Haskell cuff bracelet above, the safety chain is located on the lower left of the picture.
A safety clasp is a secure type of closure on a piece of jewelry. The term safety catch is used for a variety of these closures. On pins and brooches, a safety clasp often refers to a long pin on a hinge that can be held or released with a secure clasp (often a rotating circle within a circle).
Sapphire is a precious gemstone (a type of corundum) that ranges in color from blue to pink to yellow to green to white to purple (mauve sapphire) to pink-orange (padparadscha sapphire). Six-sided asterisms sometimes occur in star sapphires (caused by inclusions of tiny, thin, parallel needles of rutile). Sapphires are related to rubies. Sapphires were once thought to protect the wearer from poisonous creatures. Sapphire has a hardness of 9 and a specific gravity of 3.9 – 4.1. Sapphires are often heat treated to improve their color.
Sapphire quartz (also called blue quartz) is another name for blue chalcedony.
Sard is a semi-precious stone related to carnelian. This brownish-red, opaque gemstone was once used extensively for seals and was carved using intaglio. Sard was named for Sardis, the ancient capital of Lydia. Sardius is mentioned in the Bible and may refer to Jasper.
Sardonyx is a semi-precious stone that is formed by two layers, a red-brown layer of sard and a gray, white, black or brown layer of onyx. Sardonyx is a type of quartz. Sardonyx is frequently carved to make intricate cameos and seals.
A satin finish on a metal is between a matte finish and a brilliant one. This semi-glossy finish is done by making shallow parallel lines on the surface of the metal, reducing its reflectivity.
A sautoir (also known as a rope) is a long necklace (longer than opera-length), often with an ornament (a tassel or pendant) at the end. Sautoirs were common during the Edwardian era.
A scarab is a type of beetle. The ancient Egyptians used stones carved in the shape of scarabs extensively in their jewelry and other decorations. In the 1920s, after the tomb of King Tut was discovered in Egypt, Egyptian style jewelry became fashionable in the West, including scarab bracelets and necklaces.
Scarabe is a type of iridescent finish applied to some dark glass beads. The scarabe finish mimics the look of iridescent scarab beetles.
Schiller (from the German term for a play of colors or glitter) is an iridescent or bronze-like luster occurring in some minerals (it is also referred to as labradorescence when it occurs in feldspars). This optical effect is caused by submicroscopic lamella (thin layers or flakes of inclusions) contained within the mineral. These layers of inclusions can produce a bronze-like luster, golden iridescence, red color-play, and/or a blue-green sheen that flashes when viewed from certain angles. This type of inclusion can be valuable (as in sunstone and labradorite). Layers of shiller can block reflected light, decreasing the stone’s brightness. Some types of feldspars (like labradorite, sunstone, spectrolite, and peristerite) and other minerals (like hypersthene) exhibit schiller.
Sea glass (also called beach glass) is glass from old broken bottles, windows of wrecked ships, etc. that has been worn down and etched by the sea and sand over the years. This glass is smooth (with no sharp edges) and looks like beautifully sand-blasted glass with a soft patina. Pieces of this glass are collected on beaches and often made into jewelry items. Brown, deep green and clear are the most common colors of sea glass; after these come blue, amber and aqua. Rare colors include pink, red, purple, light yellow, and sea green.
Seals were once extensively used as a means of identification; they were only owned and used by relatively important people. Seals were usually mounted in rings or hung on a chain. Seals are carved in hard stones (like sard or jasper) using intaglio.
Seed pearls are tiny, round pearls that are less than 2 mm in diameter and weigh under 1/4 grain. Seed pearl jewelry was popular from the mid- to late-Victorian era when the tiny pearls were strung on horsehair to form intricate designs and were also used as accents on other jewelry.
Selenite is a soft, colorless-to-slightly-colored, transparent mineral. It is a crystalline variety of gypsum. Selenite has a hardness of 1-2 and a specific gravity of 2.3 to 2.4.
Selini was a costume jewelry company whose mark appears from the 1930s to the 1950s. Selini jewelry is usually intricate, well-designed, and often decorated with colored rhinestones and enamel. Very little is known about the company
Serpentine is a green stone; there are two types of serpentine, bowenite and hydrated magnesium silicate. Bowenite is a jade-like stone (green to black) that is sometimes used in jewelry. The softer variety, hydrated magnesium silicate, is translucent serpentine has a hardness of 4 () – 5.5 (bowenite) and a specific gravity of 2.5 to 2.6. Serpentine is found in the British Isles and some other locations. Connemara marble (from Ireland) is a type of cloudy green serpentine.
A setting is a method of securing a stone (or other ornaments) in a piece of jewelry (or other objects). There are many different types of settings, including the collet (a strip of metal surrounding the stone), the claw setting (in which prongs of metal hold the stone in place), Tiffany (a high,six-pronged setting), the cut-down setting (metal is worked around the edge of the gem, reinforced with metal ridges), pav?-set stones (stones set close together, showing no metal between them), millegrain (the stone is secured by small beads [grains] of metal), gipsy setting (with a recessed stone), and many other types (including combinations of the above-mentioned methods). Some settings are closed (there is metal behind the stone), while others are open (there is no metal behind the stone), letting light shine through the stone.
S.G. (or s.g.) is an abbreviation for specific gravity, a comparison of a material’s weight with the weight of an equal volume of water.
The shank is the part of a ring that encircles the finger.
Shiller is coppery flakes within a stone. Layers of shiller can block reflected light, decreasing the stone’s brightness. Sunstone and spectrolite often have shiller.
A signet ring is a ring that was used as a means of identification for relatively important people. The signet ring was engraved with a symbol (a coat of arms or initials) identifying a particular person. Some signet rings also had intaglio-carved seals. The earliest-known signet rings date from ancient Egypt, thousands of years ago.
Sillimanite (aluminum silicate, Al2 SiO5) is a transparent mineral that ranges in color from white to gray to brownish to greenish. Sillimanite has the same chemical formula as both kyanite and andalusite (these three minerals are polymorphs); Sillimanite is the rarest of the three (all three are used in high-temperature ceramics, used in spark plugs). Sillimanite has a hardness of 7.5 and a specific gravity of 3.2. Sillimanite is the state mineral of Delaware (since March 24, 1977); Sillimanite is found near Wilmington, Delaware. Sillimanite is found in Brazil, New England (USA), and Europe; it is found in areas of high-grade metamorphic rock.
Silver is a fine, silver-white metal often used in jewelry. Pure silver has a hardness of 2.5. Other metals are alloyed with silver (usually copper) for silver used in jewelry making. Silver tarnishes after exposure to air (a thin layer of silver-oxide forms on the surface). Silver often occurs near copper lodes.
A sleeper is a small hoop-earring made of gold that is used to keep the hole in a pierced ear open.
(also called slide charm bracelet) A slide bracelet is a type of modern-day charm bracelet made from stringing Victorian era watch fob charms together on a double chain – the charms can slide along the chains. When pocket watches (used by men) and necklace watches (used by women) went out of style after wrist watches were invented, the charms on the watch chain were removed and then strung together to make bracelets. Modern imitations are made using modern-manufactured charms.
Smoky quartz is a type of brownish quartz that has a smoky look.
A snake chain (also called a Brazilian chain) is a metal chain made up of a series of small, linked cups.
Snowflake Obsidian (also called flowering obsidian) is a volcanic glass that is usually dark (black or brownish) with white “snowflakes”. This glassy, lustrous mineral is found in lava flows, and obsidian stones can be massive. Obsidian is formed when viscous lava (from volcanos) cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35.
Soapstone (also called steatite) is a soft, easily-carved, fine-grained metamorphic rock that can be green, brown, or gray. This stone has a greasy, soapy feel to it, hence its name. Soapstone is found worldwide. It is carved into figurines, beads, seals, bowls, pipes, cookware, and other items – it has been used since ancient times. Chemically, soapstone is composed mostly of talc, hydrated magnesium silicate (Mg3Si4 O10(OH)2) plus other minerals. Soapstone has a hardness of 1-1.5 (extremely soft – it can be scratched with a fingernail) and a specific gravity of 2.2-2.8.
Sodalite is a dark blue mineral with streaks of white, gray, pink, or green. It is used for carvings and jewelry. Sodalite is one of the mineral components of lapis lazuli. Sodalite is sodium aluminum silicate chloride; its formula is Na4Al3(SiO4)3Cl. Sodalite has a hardness of 5.5 to 6 and a specific gravity of 2.1 – 2.3. Sodalite is found in Brazil, Canada, India, Italy, Namibia, United States, and Russia.
Solder is a metal alloy (a mixture of metals) that is used to join other metals. Solder melts at a lower temperature than the metals to be joined.
A solitaire is a ring set with a single stone, usually a diamond.
Souvenir jewelry is made for tourists as a remembrance of their trip. The mother-of-pearl Eiffel Tower pin above is a souvenir of Paris.
The specific gravity (abbreviated s.g.) of a material is a comparison of its weight with the weight of an equal volume of water. Specific gravity measures the density of a material.
Spectrolite is another name for Finnish Labradorite (a variety of plagioclase feldspar). It is a fairly abundant grayish mineral that has brilliant iridescent flashes of color (usually green, blue, orange, or red) after it is polished. The crystals are transparent to translucent. Spectrolite is usually cut with a flat surface in order to highlight the brilliant flashes of color. Spectrolite has a hardness of 6 to 6.5 and a specific gravity of 2.70.
A spectroscope is an instrument that is used to identify gemstones. It works by determining the light waves that a stone absorbs; different stones absorb different wavelengths of light.
Spessartine garnet (also called Spessartite garnet) is a type of a garnet that is orange (it varies from reddish orange to brownish orange to yellowish orange). The chemical composition is Manganese Aluminum Silicate. Crystals vary from transparent to translucent. This relatively rare gem is found in Sri Lanka, Australia, Madagascar, Brazil, Sweden, Myanmar, and the U.S. Spessartine garnet has a hardness of 7.0 – 7.5, a specific gravity of 4.19 (relatively heavy), and a refractive index of 1.8.
Sphene (sometimes called titanite) is a mineral that comes in green, yellow, white, brown or black wedge-shaped crystals (sphene means wedge in Greek). Sphene is used only rarely as a gem (due to its relative softness). Its chemical formula is CaTiSiO5, Calcium Titanium Silicate. Sphene has a hardness of 5-5.5, a specific gravity of 3.3 – 3.6, and a white streak.
Spinel is a very hard semi-precious stone composed of octahedral crystals. Spinel ranges in color from red to black to yellow, frequently resembling rubies. Iron and chrome are components of spinel, giving it its color. Spinel belongs to the feldspar species and is found in Burma, Sri Lanka, and Thailand. Some varieties include Balas ruby (red spinel), Almandine spinel (purple-red), Rubicelle (orange), Sapphire spinel (blue), Ghanospinel (blue), Chlorspinel (green). Spinel is also laboratory synthesized. Spinel has a hardness of 8, a specific gravity of 3.58-4.06, and a refractive index of 1.72.
A tightly-coiled ring used as a jewelry finding; it can attach charms to a charm bracelet or a clasp to a necklace or bracelet (it is like a miniature version of a keychain).
A spring ring (also known as a bolt ring) is a hollow circular metal fastening ring with a spring opening. A tiny spring keeps the arm of this clasp closed. It is used to attach two other rings or links of a necklace or bracelet. The spring ring was invented early in the 1900’s. Jewelry made prior to 1900 or so will not have a spring ring clasp.
SQUARILLION CUT (SQUARE CUT)
A Squarillion cut is a square-cut stone. This fancy cut is relatively new and is also known as a Princess or Quadrillion cut.
SS is an abbreviation for sterling silver.
Stabilized stones have been impregnated with plastic to improve its durability, stabilize cracks, and improve the stone’s appearance (a dye is sometimes added to the plastic – this is called a color shot or color stabilized). Liquid plastic resins are injected into soft, porous stone at high pressures – the plastic fills the pores in the stone. Turquoise is often stabilized.
Steel containing chromium and is resistant to rust and corrosion.
STAINLESS STEEL JEWELRY
Stainless steel(316L) is the hottest trend, especially in men’s jewelry. Perfect in its simplicity yet very resistance to corrosion and other reactions.
STAR OF AFRICA
The Star of Africa (also called the Cullinan diamond) is the largest diamond yet found, weighing 3,106 carats (roughly 1.3 pounds) in its rough form. It was mined at the Premier Mine in South Africa in 1905. This enormous gem was named for the chairman of the company that owned the mine. It was given to King Edward VII of England for his birthday in 1907. The diamond was cut (by Joseph J. Asscher of Amsterdam) into many stones, including the Cullinan I (530 carats, pendelique-brilliant shaped, the largest cut diamond in the world), the Cullinan II (317 carats, cushion-shaped), Cullinan III (94 carats, pendelique shaped), Cullinan IV (63 carats, square-brilliant shaped), and many other smaller stones.
STAR OF INDIA
The Star of India is a huge, blue, star sapphire weighing 563.35 carats. It is cut as a cabochon. This gemstone was found in Sri Lanka (date unknown). A British Army officer brought it to London, where it was cut by Albert Ramsay around 1905. It is now at the American Museum of Natural History.
STAR OF THE SOUTH
The Star of the South is the largest diamond found in South America. This Brazilian stone weighs 254.5 carats.
A “star garnet” is almandine that exhibits an asterism. Almandine is a type of garnet that ranges in color from deep red to reddish-brown.
A “star ruby” is a ruby that exhibits an asterism, a six-pointed star of light (when cut as a cabochon). The world’s biggest star ruby is the Rajaratna, which weighs 2,475 carats. The world’s biggest double-star ruby (with a 12-pointed star) is the Neelanjali, weighing 1,370 carats.
A star sapphire is a sapphire that exhibits an asterism in the form of a colorless, six-rayed star that reflects light. Star sapphires are cabochon cut. Laboratory-produced star sapphires (“Linde stars”) were developed in 1947 by the Linde company; most star sapphires today are synthetic.
A star setting is one in which a gem is set within an engraved star; the gem is secured by a small grain of metal soldered to the base of each ray of the star. This type of setting was popular in the 1890s.
Steatite (also called soapstone) is a soft, easily-carved, fine-grained metamorphic rock that can be green, brown, or gray. This stone has a greasy, soapy feel to it, hence its name. Soapstone is found worldwide. It is carved into figurines, beads, seals, bowls, pipes, cookware, and other items – it has been used since ancient times. Chemically, soapstone is composed mostly of talc, hydrated magnesium silicate (Mg3Si4 O10(OH)2) plus other minerals. Soapstone has a hardness of 1-1.5 (extremely soft – it can be scratched with a fingernail) and a specific gravity of 2.2-2.8.
The step cut is generally used for colored stones. This cut is a rectangular to square and has many facets parallel to the edges of the stone.
Sterling is silver with a fineness of 925, that is, sterling is 925 parts per thousand (or 92.5%) silver and 7.5 parts per thousand (or 7.5%) copper (the copper increases the silver’s hardness). Sterling is quite malleable.
Strass is a highly reflective glass that is made to imitate gemstones. The original rhinestones were quartz stones obtained from the Rhine river. These stones were cut to resemble gemstones.
The streak of a mineral is its color when it is in powdered form. You can determine the streak of a mineral easily by rubbing a rough mineral (not cut stones!) along the surface of a hard, unglazed porcelain sheet (this is called a streak plate – you can use the back of a white porcelain bathroom tile). Even though the color of a mineral may vary, the streak color is constant. Note: the streak plate has a hardness is about 6.6, so it can only test mineral that is harder than that (since they must leave a streak on the porcelain). For example, the streak of chalcopyrite, graphite, magnetite, and pyrite is black, the streak of galena is gray, the streak of cinnabar, the streak of azurite and lapis is blue, the streak of malachite is green, the streak of turquoise is white with a green tint, the streak of olivine, amethyst, and tourmaline is white, and the streak of hematite is red-brown.
Striations are grooves, lines and scratches found naturally in some minerals.
Sugar beads are beads that look as though they were rolled in granulated sugar; the fine grains on the surface of the beads are in fact tiny grains of glass (or plastic). Delicate glass sugar beads were made in Gablonz and Japan early in the 20th century.
Sugilite is a medium to dark purple semi-precious gemstone (it can also range from pink to brown to black). It is usually opaque with a waxy luster (but can be translucent) and often has brown, pink and white inclusions, looking like a purple version of turquoise. It is usually polished and not faceted. Sugilite has a hardness of 5.5-6.5 and a specific gravity of 2.75 – 2.80. This stone is not enhanced – massive stones are often found. Sugilite is Potassium Sodium Lithium Iron Manganese Aluminum Silicate; its formula is KNa2Li3(Fe, Mn, Al)2Si12O30. This stone was named for Ken-ichi Sugi, the Japanese geologist who discovered it in 1944. It is found in Iwagi Island, Shikoku, Japan, and Mont Saint-Hilaire, Quebec, Canada, but the largest deposits are in northern South Africa.
Sunstone is also called aventurine feldspar (a variety of oligoclase). This gemstone varies from golden to orange to red-brown, and can be transparent or translucent. Sunstone is metallic-looking due to sparkling red, orange or green crystalline inclusions (these are hematite or goethite crystals). Sunstone is found in Canada, the USA (in Oregon), India, Norway, and Russia. This brittle stone has a hardness of 6 and a specific gravity of 2.63 – 2.67. Sunstone is not enhanced.
Stainless steel—a non-allergenic material when not plated. It is darker and grayer than sterling silver.
Swarovski is an Austrian company that makes high-quality rhinestones, beautiful cut crystals, costume jewelry, and other glass-related items. The company was founded by Daniel Swarovski (1862-1956), the son of a glass faceter. In 1892, Daniel developed a new mechanized technique for faceting glass crystals, creating a sparkling, diamond-like “chaton.” He then started a factory (and company) in Wattens, Austria (in the Tyrolean Alps) in 1895. In the 1970’s, the company expanded to the Providence, Rhode Island, USA – they later moved to Cranston, Rhode Island. In 1955, Swarovski and Christian Dior developed the iridescent aurora borealis stone. The company began a line of rhinestone costume jewelry in 1977. Since 1988, the Swarovski logo has been a swan (before 1988, the logo was an edelweiss flower).
Swiss lapis is not lapis lazuli at all. It is jasper dyed to resemble lapis lazuli and is misleadingly called “Swiss lapis.”
Synthetic rubies were first made by the French chemist Auguste Verneuil, who invented the flame-fusion process for producing inexpensive rubies in 1886. It was a ruby, but it didn’t look much like one. In 1918, J. Czochralski invented the pulling method for growing inexpensive rubies. Carroll Chatham synthetic rubies (more expensive to produce, but natural-looking) was introduced in 1959. Kashan synthetic rubies were made beginning in 1979.
Synthetic stones are made in laboratories; these stones generally lack imperfections. They are very hard to distinguish from natural stones.
Tabasheer (also spelled tabashir) or pearl opal is an organic stone that forms in damaged joints (nodes) of bamboo plants. This hydrated form of silica appears as a rounded mass of opal, and looks like seed pearls.
The table is the large, flat area at the top of a cut gemstone.
Tahitian pearls (also called black pearls) are dark-colored pearls. They are produced by the large, black-lipped pearl oyster Pinctada margaritifera (also called the Tahitian black pearl oyster), a mollusk found in the tropical Indo-Pacific Ocean. Black pearls come in many colors, including many body shades and overtone tints including gray (light gray to almost black), peacock green (especially valuable), aubergine (eggplant), and deep brown. The color of the dark nacre is determined by the minerals in the oyster’s diet (plankton) and in its environment. Many “black pearls” are dyed or irridiated to enhance or change their color; it is difficult to tell a natural pearl from a treated pearl. Tahitian pearls are graded on six factors: 1.Shape (round is most valued), 2.Size (the larger the better), 3.Surface Quality= (clean is superior to blemished), 4.Luster (the more high-gloss luster the better), 5.Nacre Thickness (thicker is better and longer lasting), and 6.Color (overtones atop the body color add value to the pearl. The most sought-after color is peacock green and darker colors are more valuable Overtone colors include blue, pink, gold, silver, aubergine, and peacock green).
Tanvorite is a trademarked name for a manmade gemstone. This synthetic stone is a deep blue-purple stone that resembles tanzanite.
Tanzanite (strontium-rich Calcium-aluminum silicate) is a valuable, transparent, blue-violet type of zoisite resembling sapphire. Tanzanite has a hardness of 6 and a specific gravity of 3.35. It is often heat-treated in order to produce a deeper blue-violet color. This mineral was discovered in 1967 by Manuel d’Souza (an Indian tailor) southwest of Mt. Kilimanjaro in Tanzania, Africa.
Taxco is a town in the State of Guerrero in Mexico that is famous for its silver jewelry production. The American silversmith William Spratling, set up shop in Taxco in 1929, and many other silversmiths followed. Early Taxco jewelry is avidly collected. Modern pieces are distinguished by a registration mark of two letters followed by a series of numbers (this mark was required by the Mexican government since 1979).
To temper is to strengthen or harden metal (or glass) by heating it or by heating then cooling it. Harder tempers are stronger, more spring-like, and brittler (when they are bent, they may break). Softer tempers are weaker but bend easily.
A tennis bracelet is a simple, flexible, in-line diamond bracelet. The name tennis bracelet was first used when the great tennis player Chris Evert dropped a diamond bracelet during a tennis match in the summer of 1987 (at the US Open Tennis Tournament). She had to stop the match until she found her bracelet. Since then, that style of bracelet has been called a tennis bracelet.
Thermoluminescent minerals emit bright light when heated. For example, chlorophane is a variety of fluorite that emits a bright green light when heated.
Thermoset plastic (also known as thermoplastic) is a hard, non-rigid synthetic substance that cannot be melted by reheating. Thermoset plastic is formed under high heat or pressure by a process known as polycondensation. Bakelite is a thermoset plastic. The bangle above is “butterscotch” bakelite.
The son of Charles Lewis Tiffany, who founded the legendary jewelry firm which bears his name, designer Louis Comfort Tiffany was an early exponent of the Art Nouveau movement and later moved on to become famous for his Favrile iridescent glassware.
The Tiffany setting is a ring with a high, six-pronged solitaire diamond on a simple circular band. This design was introduced by Tiffany & Co. in 1886.
Tiger’s eye is a yellowish-brown to reddish-brown gemstone that has a silky luster. This gemstone has bands of yellow and brown; when viewed from the opposite direction, the colors are reversed. Tiger’s eye is usually highly polished and set as a cabochon (or cut as a bead) to display the stone’s chatoyancy (light reflected in thin bands within the stone). Tiger’s eye is a type of chatoyant quartz with fibrous inclusions (especially crocidolite). This stone is sometimes heat-treated. Tiger’s eye has a hardness of 7.0. Most tiger’s eye is mined in South Africa, but it is also found in Australia, Brazil, Burma (Myanmar), India, Namibia, Sri Lanka (Ceylon), and the USA. Green-grey varieties of this stones are called cat’s-eye quartz. Blue-grey to bluish varieties are called hawk-eye. Deep brown varieties of this stone are called bulls-eye or ox-eye.
A metallic element that has been used mainly in industry, but also used in some jewelry because of the range of colors it produces when heated.
A toggle clasp (also called a bar and ring clasp) is a jewelry fastener in which a bar can be inserted into a ring to fasten a piece of jewelry. It is used to attach the two ends of a necklace or bracelet.
Topaz (aluminum silicate fluoride hydroxide) is a very hard gemstone that ranges in color from brown to yellow to blue to pink. Pink topaz is usually created by irradiating common yellow topaz. Other colors are often created by heat-treating and/or irradiating topaz. Imperial topaz is golden orange-yellow topaz; it is the most valuable topaz Topaz has a hardness of 8 and a specific gravity of 3.5-3.6. Topaz may have been named for the legendary Topasos Island in the Red Sea.
A torque (also spelled torc) is a necklace that consists of a narrow, twisted band made of metal. This type of ornament was worn by the ancient Celts, Britons, and Gauls.
A torsade is a necklace made of many strands that are twisted together.
Tortoiseshell is the shell of a tortoise. It was used in the 1800’s for jewelry, hair combs, and other ornaments but is banned today. Tortoiseshell inlaid with precious metals is called pique. Tortoiseshell will burn easily, and smells like burning hair. It is easily imitated by plastic, but its smell when burnt is very different. Tortoiseshell has a hardness of 2.5 and a specific gravity of 1.29.
Tourmaline is a dichroic gemstone that comes in many, many different colors; it also appears to have different colors depending on the angle at which it is seen. Tourmaline has the greatest color range of any gemstone – the lighter colors are more valuable than the darker colors. It ranges in color from pink to green to red (rubellite) to purple to blue-green (indicolite) to colorless (achroite) to black. Watermelon tourmaline is both pink and green. Tourmaline occurs as an elongate three-sided prism and is mined in Brazil, The Ural mountains in Russia, Namibia, Sri Lanka, and California. Tourmaline was only discovered in the 1700’s. Tourmaline has a hardness of 7-7.5 and a specific gravity of 3.02-3.25. It is doubly-refractive.
Tourmalinated quartz is a variety of transparent quartz that has needle-like inclusions of black to dark green tourmaline crystals. This beautiful stone is found worldwide. Tourmalinated quartz has a hardness of 7.0. This stone is not enhanced.
Translucent materials allow light to pass through them, but the light is diffused (scattered). Some translucent stones include moonstones, opals, and carnelian. Lucite and other plastics can also be translucent.
Transparent materials allow light to pass through them without diffusing (scattering) the light. Some translucent stones include diamond, zircon, emerald, rock crystal, and ruby. Plastics like lucite can also be transparent. In the confetti lucite bangle above, the glitter within the lucite is visible.
Transvaal jade is not jade; it is a green to gray massive variety of grossular garnet, calcium-aluminum silicate. It is found about 40 miles west of Pretoria, South Africa. Transvaal jade can be distinguished from jadeite or nephrite by its high refractive index. Grossular garnet has a refractive index of 1.72 to 1.73, a hardness of 6-7.5 and a specific gravity of 3.5 – 3.67.
Traprock is a type of igneous rock. This solidified lava often contains pockets of crystals.
Trapiche emeralds are rare, valuable emeralds that have a black, six-rayed star within them, caused by black carbon impurities (the star is not an asterism). These stones are usually cabochon cut to display the beautiful spoke-like star. These stones are only mined in Colombia, South America. Trapiche emeralds are sometimes called star emeralds (but the term star emerald can also refer to emeralds with an asterism). Trapiche is a Spanish word for the spoked wheel that is used to grind sugar cane.
A trembler is a piece of jewelry that has a part (or parts) set on a spring; the spring-set parts move as the wearer of the jewelry moves.
Trifari is a pre-eminent jewelry manufacturing company that produces high-quality and beautifully-designed pieces. The company began as Trifari and Trifari in 1910, founded by Gustavo Trifari and his uncle; a few years later, his uncle left and the company was simply Trifari. Leo Krussman joined Trifari in 1917. In 1918, when Carl Fishel joined the company, they renamed the company Trifari, Krussman and Fishel (their hallmark was T.F.K.). Alfred Philippe, who had been a jewelry designer for Cartier and Van Cleef & Arpels, designed pieces for Trifari for many years. Some other Trifari designers included Jean Paris (1958 -1965), Andre Boeut (1967 – 1979), and Diane Love (1971 – 1974). Trifari was owned by the Hallmark Company from 1975-1988, and by Crystal Brands from 1988-1994. It was then part of the Chase Capital division of the Monet Group, which later went bankrupt and was bought by Liz Claiborne (2000). The classic pin and earrings set above have paste rubies, emeralds, sapphires, and diamonds (and was designed by Alfred Philippe, about 1947-8).
The trillion cut is a triangular cut based upon a brilliant style cut (and not a stepped facet). The corners of the triangle are truncated (cut short) and there are a variety of facets, giving this cut a sparkling brilliance.
A triplet is a manufactured stone that is made by sandwiching three thin layers of stones together. For example, an opal triplet had a top, protective layer of clear quartz, a thin middle layer of opal, and a base layer of dark, color-enhancing matrix (usually black onyx or ironstone).
Precious metals (like gold, platinum, and silver) are measured in troy weight, which has units of pennyweights, ounces, and pounds. Troy ounces and pounds are different from everyday US measures.
1 pennyweight 24 grains = 1.5552 grams
1 Troy ounce = 20 pennyweight 31.1035 grams
1 Troy pound = 12 Troy ounces 373.24 grams
Tsavorite is a rare, deep green variety of grossular garnet, a type of garnet, calcium-aluminum silicate. The emerald green color comes from vanadium and chromium. Tsavorite is similar to emerald, but is rarer and more durable; it also has a higher refractive index, 1.74. Tsavorite stones over two carats are considered large and are very rare. Tsavorite has a hardness of 7.5 and a specific gravity of 3.6. Tsavorite is found in East Africa; it was named by Harry B. Platt of Tiffany & Co. for the Tsavo National Park in Kenya, where this gemstone was originally found in 1967. Tsavorite is not enhanced.
Tumbled stones were finished in a tumbler, a mechanical device that smoothes and rounds the surfaces of stones. Tumbled stones look very much like stones that have been in a fast-flowing river or stream for a long time.
A tumbler is a rotating cylinder (powered by a motor) that smooths and rounds the surfaces of stones, increasing their luster. As the stones tumble around the cylinder, they bump against each other and smooth each other’s surfaces.
Turquoise is a non-translucent, porous semi-precious stone that is usually cut as a cabochon. Turquoise was first found in Turkey, hence its name. Turquoise is found in desert regions worldwide. Persian turquoise is robin’s egg blue and has no matrix (streaks of the mother stone from which they were found). North American turquoise is greener and has a matrix streaks. Over the years, oil from your skin is absorbed by the stone and it will change color slightly. Turquoise has a hardness of 6 and a specific gravity of 2.60-2.85.
Twinning is a common error in crystallization in which two crystals grow out of one another or next to one another, and their crystal lattice is oriented differently from one another (some twins are like a mirror image of each other). If the crystals have grown into one another, they are called penetrant twins (forming a cross-shape like Staurolite, a star-shape like Muscovite, and other unusual shapes). If the crystals are mirror images that grow next to one another, they are called contact twins (they are often likened to Siamese twins). Twinning can drastically change the outward symmetry of the mineral specimen, by either increasing or decreasing the symmetry (like with spinel). For example, twinning can make an orthorhombic crystal appear to be hexagonal (as in Aragonite).
A machine that cleans jewelry by vibrating a solution at an ultra-high frequency. Capable of cleaning tiny cavities of a jewelry piece without scratching the surface but can damage soft or brittle gems. Never to be used on pearl jewelry.
Unakite is an opaque mineral that is green with patches of red and pink. Unakite is a variety of granite that contains green epidote and pink feldspar (but lacks mica). It has a hardness of 6 to 7 and a specific gravity of 2.86 – 3.2. Unakite was named for the Unaka Mountains in Tennessee, USA. Unakite is found in the USA and Africa.
Urea bakelite is a type of thermoset plastic.
Vabanite is a type of brown-red jasper with yellow flecks that is found in California, USA.
Variscite, AlPO4-2H2O, Hydrated Aluminum Phosphate, (also called Utahlite) is a relatively rare translucent pastel green to emerald green gemstone with blue or yellow overtones (it is similar to chrysocolla, chrysoprase and turquoise). Variscite is found in the USA (in Utah and Nevada), Germany, Brazil, and Australia (in Queensland). Variscite has a hardness of 4.0 – 5.0 and a specific gravity of 2.57. It is not enhanced.
The Vendome label was made by Coro beginning in 1944. Vendome was a high-end subsidiary of Coro, replacing the Corocraft label. Helen Marion was the principal designer for the Vendome line beginning in the early 1960’s.
VENUS’ HAIR STONE
Venus’ hair stone is another name for rutilated quartz.
Vermeil is gold-plated silver. Less occasionally, gold-plated bronze is referred to as vermeil.
The Victorian era was the time when Queen Victoria ruled Great Britain (1837-1901). Many different styles of jewelry developed during this era.
Vienna turquoise is fake turquoise made by compressing a precipitate of aluminum phosphate (colored with copper oleate).
A vinaigrette is a tiny, decorative bottle or box that was often carried on a chatelaine. Smelling salts or aromatic vinegar was carried in the vinaigrette.
A classic, characterized by excellence, maturity, and enduring appeal.
The term “vintage” is often misunderstood by dealers and collectors. When dealing with vintage costume jewelry, the term usually applies to an item that is 20+ years old. Many experts agree that the term “antique” can be applied to vintage costume jewelry that is 50+ years old. This may be for several reasons. But the main reason is the field of collecting costume jewelry is fairly new.
Vitreous means glass-like.
Vogue was a costume jewelry company that was founded in 1936 by Harold Shapiro (father of the founder of the Les Bernard company), Jack Gilbert, and George Grant. Their jewelry was sold through I. Magnin and other stores. They went out of business in the 1970’s.
Volcanic glass is another name for obsidian.
VS clarity diamonds are of superior quality and frequently used in fine jewelry. The grade signifies that minor inclusions are difficult to see, even under 10x magnification.
Vulcanite (also called ebonite) is a hard, moldable, polished dark colored (ranging from brown to black) early rubber. Vulcanite was produced by adding sulfur to vulcanized rubber. It was used for combs, ornaments, and buttons. It is not the same as gutta percha.
Watermelon tourmaline is a tourmaline gemstone that is multicolored, going from pink to green. The Schreiner pin above is made of paste (glass) watermelon tourmaline.
“Water sapphire” is not a true sapphire, but is iolite, a more common, softer, and much less expensive mineral. It is a transparent, violet-blue, light blue or yellow-gray mineral. Iolite is pleochroic; a single stone will show many colors (in the case of Iolite, violet-blue, light blue, and yellow-gray). Iolite has a hardness of 7 – 7.5. Iolite is found in Sri Lanka, India, Madagascar, and Burma.
Wax pearls are hollow glass beads that are filled with wax and resemble pearls.
WEDDING CAKE BEADS
Wedding cake beads are lamp worked glass beads that are decorated with intricate, colorful glass overlays, often of roses and decorative swirls and dots. This type of bead was originally made in Murano, Italy.
Wedgwood is an old pottery company that also makes some porcelain jewelry. The company was founded in Burslem, England in 1752 by Josiah Wedgwood (1730 – 1795), who was Charles Darwin’s grandfather. Their signature Jasper ware (white on blue porcelain formed into a cameo) is made into pins, pendants, and necklaces.
The Weiss company made high-quality costume jewelry from 1942 until the 1970’s. The company was founded in New York City by Albert Weiss, a former employee of the Coro Company (the largest costume jewelry manufacturer). Weiss’ jewelry was often studded with Austrian rhinestones.
Welding is a process that joins two pieces of metal using very high heat. Rolled gold is formed in this fashion.
White gold is gold that has been alloyed with a mix of nickel, zinc, copper, tin, and manganese (and sometimes palladium). White gold was originally developed to imitate platinum during World War II (during this time in the US, platinum was considered a strategic material and its use was prohibited for most non-military applications, like jewelry making).
Xaga is a type of obsidian found in California, USA.
Xalostocite is a pink grossular garnet that is found in a matrix of white marble. Xalostocite is found in Xalostoc, Mexico.
Xyloid jasper is jasperized wood (petrified wood). It is wood that has fossilized – all the original chemicals have been replaced with minerals, making a stone-like replica of the original wood.
YAG is an acronym for yttrium aluminum garnet, a man-made imitation diamond. This imitation stone lacks the fire of a natural diamond.
In its natural state gold come in varying shades of yellow. Relatively pure when initially mined, gold is usually alloyed with copper, zinc, and/or silver when used in jewelry making.
YGF is an abbreviation for yellow gold filled.
Zamak is a zinc alloy containing some aluminum (3.9-4.5%) and copper (0.02-0.05%).
Brittle at room temperature but malleable when heated, this bluish-white metal is used to form alloys such as Brass, Bronze, and Nickel Silver.
Zircon (zircon silicate) is a lustrous gemstone that comes in colors ranging from golden brown to red to violet to blue. Pure zircon is colorless, but most zircon stones are brown. Zircon stones can be heat-treated to become blue or colorless; sometimes, heat-treated stones revert to their original color. Clear zircon is sometimes sold (intentionally or otherwise) as diamond. It has a hardness of 7.5 and a specific gravity of 3.90-4.71.
Zoisite (Calcium-aluminum silicate) is a gray-green mineral that occurs in cracks of igneous rock. Zoisite has three known forms: anyolite (a green matrix containing rubies), tanzanite (transparent, blue-violet containing strontium), and thulite (opaque pink crystals containing manganese). Zoisite was named for the Slovenian mineral collector Baron Sigismund Zois von Edelstein, who financed the expedition that discovered Zoisite.