Blackstone:  Deep black jasper.

Bloodstone:  Naturally occurring stone which is a type of chalcedony.  African blood stone is opaque moss green with mottled red and gray inclusions called Seftonite.  Indian bloodstone is a deep green and white with red spots called heliotrope.  Bloodstone is said to give courage.  To clean your bloodstone, avoid harsh detergents.  Wash with warm, soapy water and dry thoroughly.  Never clean ultrasonically.  Never steam clean.

Bog Oak:  Fossilized peat - found mainly in 19th century Irish jewelry.

Bookchain:  Folded over square or rectangular links often engraved.

Boro Bead:  Made from borosilicate (hard glass).  Has a higher melting temperature than "soft glass" or effetre.

Cairngorn:  A smoky grayish brown, smokey yellow to almost black variety of transparent crystalline quartz.  Often found in vintage jewelry from Scotland.

Cameo:  A carved gem that is actually a miniature bas-relief sculpture.  Commonly carved from materials of differently colored layers such as onyx, shell and coral.

Carat:  Unit of weight for gemstones.

Carnelian:  A translucent form of chalcedony which is named for the deep red-orange color of the Kornel cherry.  Its color comes from iron oxide. Said to be a stone of protection.  To clean your carnelian, avoid harsh detergents.  Wash with warm, soapy water and dry thoroughly.  Never clean ultrasonically.  Never steam clean.  Moh's scale of hardness:  6.5.

Casting:  Forming an object by pouring molten metal into a mold.

Cat's Eye Quartz:   Has fine parallel internal lineations which produce a silver white line that moves as the stone moves.  Believed to foster serenity.  To clean your cat's eye quartz, avoid harsh detergents.  Wash with warm, soapy water and dry thoroughly.  Never clean ultrasonically and never steam clean.  Moh's scale of hardness:  8.5.

Celluloid:  Semi-synthetic Thermoplastic which is part natural fiber (cellulose) invented by John Wesley Hyatt in 1868.  One of the major drawbacks was its flammability.  In 1927, the Celluloid Corp. introduced cellulose acetate which substituted acetic acid (vinegar) for nitric acid and camphor, and is non-flammable.  When warmed in hot water, celluloid smells like camphor and cellulose acetate smells like vinegar.  Do not immerse pieces with rhinestones.

Chalcedony:  (cal SID nee)  Variety of quartz.  Composed of microcrystalline quartz crystals and dydrated silica (opal).  To clean your chalcedony, avoid harsh detergents.  Wash with warm, soapy water and dry thoroughly.  Never clean ultrasonically and never steam clean.  Moh's scale of hardness:  7.

Channel Set:  Stones are set in a metal channel and held in place by a slight rim that runs along the edge of the channel.

Chaton:  Stone with eight facets on top and eight facets on the bottom.  The top is flat and the bottom comes to a point.

Chatoyant:   Having a lustre that seems different colors in different lights.

Chrome Diopside:  Member of the pyroxene family and contains chromium, which gives it the deep green color.  To clean your chrome diopside, avoid harsh detergents.  Wash with warm, soapy water.  Never clean ultrasonically.  Never steam clean.  Moh's scale of hardness:  5.5 - 6.

Chrysanthemum Stone:  From China.  Opaque medium red-brown with lighter flower-shaped bursts of color.  Said to be a stone of harmony and change.