| Term |
Diamond Glossary by rab for Paul Van den Eynde |
| Carat Weight |
The metric carat, which equals 2 milligram, is the standard unit of weight for diamonds and most other gems. If other factors
are equal, the more a diamond weighs, the more valuable it will be. |
| Cavity |
An inclusion consisting of a large or deep opening in the diamond. |
| Certificate | Laminated document by a gemological institute to describe a Diamond's characteristics. |
| CGL | Central Gem Laboratory, established in 1970 in Tokyo. Diamond grading and Identification. Grading of excellent cut and 'Hearts and Arrows'. Overseas office in cooperation with the HRD in Antwerp since 1992. |
| Chip |
A tiny piece missing, caused by normal wear and tear, or by cutting. |
| Clarity |
A diamond's relative position on a flawless to imperfect scale. Clarity characteristics are classified as inclusions (internal) or
blemishes (external). The size, number, position, nature, and color or relief of characteristics determine the clarity grade. Very
few diamonds are flawless, that means, show no inclusions or blemishes when examined by a skilled grader under 10X
magnification. If other factors are equal, flawless diamonds are most valuable. |
| Cloud |
A group of tiny white inclusions which result in a milky or cloudy appearance. |
| Coated Diamond |
A diamond colored by a surface coating which masks the true body color; the coating may be extensive (entire pavilion, for
example), 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 diamond's body color approaches colorlessness. Most
diamonds have at least a trace of yellow or brown body color. With the exception of some natural fancy colors, such as blue,
pink, purple, or red, the colorless grade is the most valuable. |
| Crown |
The upper part of the diamond above the girdle. Consists of a large flat area on top called a table, and several facets below it. |
| Culet |
The smallest facet at the bottom of the diamond. |
| Cut |
The proportions and finish of a polished diamond (also called make). Cut can also mean shape, as in emerald cut or marquise
cut. Proportions are the size and angle relationships between the facets and different parts of the diamond. Finish includes polish
and details of facet shape and placement. Cut affects both the weight yield from rough and the optical efficiency of the
polished diamond; the more successful the cutter is in balancing these considerations, the more valuable the diamond will be. |
| CZ | Cubic zirconia. A widely used simulant, an imitation for a natural diamond. |
