Loose Diamond Definitions: C

Cabochon-An unfaceted cut stone of domed form.

Canary-A term referring to diamonds with an intense yellow hue.

Canary Diamond-An intensely colored "yellow" diamond.

Carat-A unit of weight for diamonds and other gems

Carat Weight-The metric carat, which equals 0.200 gram, is the standard unit of weight for diamonds and most other gems.

Carbon-An inclusion in a diamond that appears black to the unaided eye.

Carbon Pinpoints-The same as carbon spots but extremely small and somewhat more likely to be opaque.

Carbon Spots-Any black-appearing inclusion or imperfection in a diamond.

Cavity-An opening on the surface of a fashioned diamond.

Central Gem Laboratory-Central Gem Laboratory, established in 1970 in Tokyo. Diamond grading and Identification. Grading of excellent cut and 'Hearts and Arrows'.

Certificate-Laminated document by a gemological institute to describe a Diamond's characteristics.

Certified Gemologist-A title awarded by the American Gem Society to qualified jeweler-members.

Champagne Diamond-A greenish-yellow to yellow-green diamond of a sufficiently pronounced hue to be an asset.

Change of Color-A phenomenon of some colored stones in which the gem material appears a different color in different types of light.

Clarity-A stone's relative position on a flawless to imperfect scale.

Clarity Grade-One of the four value factors of a diamond. Diamonds are ranked on a scale from flawless to included.

Clean-A term used by some jewelers to mean absence of internal imperfections.

Closed Culet-A culet on a diamond that is too small to be resolved with the unaided eye and that can be seen only with difficulty under 10x. The term is rarely used to refer to a pavilion point or ridge with no "culet."

Closed Table-A term used by some diamond men to designate a small table diameter.

Cloud-A group of tiny white inclusions which result in a milky or cloudy appearance.

Cloud Texture-A group of tiny white inclusions, composed of minute hollow spaces, or very small patches of tiny crystals or other impurities that produce a cottony or clouded appearance in a n otherwise highly transparent diamond.

Coated Diamond-A diamond colored by a surface coating which masks the true body color; the coating may be extensive, but is more often limited to one or two pavilion facets or a spot on the girdle.

Color-Grading color in the normal range involves deciding how closely a stone's body color approaches colorlessness.

Color Change-A phenomenon of some colored stones in which the gem material appears a different color in different types of light. This is caused by selective absorption and/or transmission of the specific type of light to which the gemstone is exposed.

Color Grade-One of the four value factors of a diamond.

Colored Stone-All natural gemstones except for diamonds or colored diamonds

Commercially Clean-The common meaning of this term is "reasonably free from inclusions."

Critical Angle-The largest angle measured from the normal at which light can escape from and optically dense substance, and the smallest angle to the normal at which light is totally reflected within the dense substance.

Cubic Zirconium- A widely used fake, an imitation for a natural diamond.

Culet-The small facet that is polished parallel to the girdle plane across what would otherwise be the sharp point or ridge that terminates the pavilion of a diamond or other gemstone.

Cultured Pearl-A pearl produced by implanting A shell bead or mantle tissue into the body of A pearl bearing mollusk.

Cushion Cut-The older form of the brilliant cut, having a girdle outline approaching a square with rounded corners.

Cut-The proportions and finish of a polished diamond.

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