Cabochon - a gemstone cut with a curved or domed top surface without any facets or flat surfaces. This cut is usually used for opaque gemstones.
Cameo - a gemstone or shell material having different colors carved to show in low relief the design and the background in contrasting colors.
Carat Weight - a unit of weight for gemstones. This unit of weight originated from the carob seed because of its uniformity. One carat equals 0.200 grams.
Channel Setting - gemstones mounted in a row into a deep groove in a piece of jewelry. The edges are parallel and bent over the girdle of the gemstones to secure them. Gemstones set in this fashion are usually flush with the surface of the piece of jewelry.
Choker - a short necklace 15" or less worn high on the neck.
Clarity - refers to a gemstone's internal characteristics and surface
blemishes. (I also like to refer to them as the gemstone's fingerprints
or birthmarks. Just like people, no two gemstones will ever have the
same fingerprints or birthmarks.) Although clarity refers to both diamonds and colored gemstones, they each have their own grading systems which are similar but not the same.
Color (diamonds) - refers to the diamond's natural tint or bodycolor. The most common
colors are yellow, brown and gray. The color scale runs from D
(colorless, the highest and rarest grade) to Z (light yellow, brown or
gray). This scale is broken down into five groups:
D-E-F - colorless
G-H-I-J - near colorless
K-L-M - faint yellow, brown or gray
N-O-P-Q-R - very light yellow, brown or gray
S-T-U-V-W-X-Y-Z - light yellow, brown or gray
(Note: each letter grade of the color scale has its own range within the scale.)
Color (colored gemstones) - is graded differently than diamonds. For colored gemstones color is graded for its hue, tone and saturation.
Crown - the part of a facetted gemstone above the girdle.
Culet - a small facet that runs parallel to the table placed at the bottom of a gemstone where it would normally come to a point. A culet is added to a gemstone for one of two reasons:
to protect the point of the gemstone from being chipped or broken during handling.
as a cutter's signature to show that he/she took the added time to completely finish off the gemstone.
Cultured Pearl - a pearl produced by artificially promoting its growth by inserting an irritant into the flesh of a mollusk. This irritant is usually mantle tissue or a small pearl bead.
Cut - refers to the proportions of the diamond and the arrangement of its
facets. Do not confuse cut with the shape of the diamond. Cut is the
most important of the 4 Cs. This is what determines the amount of
brilliance as well as spectral colors of the rainbow the diamond will display.
For colored gemstones, cut refers to many things which we summarize as the make of the gemstone. This includes both the proportion and finish. It also includes the shape as well as the face up outline and facet design.