A Glossary of Jewelry Terms: C

Cabochon

A round gem with a high polish and no facets.

Carat

Often confused with karat, carat, abbreviated as CT, measures the weight of a gemstone. One carat equals 200 milligrams.

Certification

A blueprint listing the characteristics, flaws, and details of a gem. Diamonds receive a Diamond Grading Report, and other gems receive a Gemological Identification Report.

Clarity

A gem’s rating based upon the amount of flaws it has. Clarity is designated with letters. F indicates flawless. IF indicates internally flawless with slight blemishes. VVSI indicates very, very slightly included. VSI indicates very slightly included. SI indicates slightly included. I indicates included. This category has flaws visible to the naked eye.

Cluster

1. A group of pinpoint inclusions in a gemstone.
2. A setting in which several small stones surround a large central stone.

Color

In diamonds, this refers to the absence or presence of color in a white diamond. Color rating begins at D, which has absolutely no color, and moves along the alphabet to Z, which designates light yellow diamonds. Note that diamonds marketed as yellow diamonds do not fall within this category.

Costume Jewelry

Cheaper jewelry made to replicated more expensive pieces. Usually, it is made with inexpensive materials but sometimes has precious plating and real gems. Its name comes from actors who use it for stage productions. Intended for fun, everyday use.

Cut

Unrelated to shape, the term cut takes proportions, polish, and symmetry into consideration for valuation purposes. Five cut ratings exist: Excellent, Very Good, Good, Fair, and Poor. A cut’s quality determines the brilliance, fire, and scintillation of a gem.