Diamond Terms

Speaking the jeweler’s language:

BLEMISH: A flaw on the exterior of a diamond, such as a scratch, abrasion, nick or chip.

BLUE-WHITE: Refers to a diamond that glows (flouresces) blue under ultraviolet light.

BRILLIANCE: White light reflected back from a diamond.

BRILLIANT: A round diamond with 58 facets.

CARAT: A unit of weight, equal to 200 milligrams. In ancient times one carat was equal to one carob bean or four grains of rice.

CARBON: The raw material of which diamonds are made. Occasionally a diamond will contain tiny pockets of carbon which can be seen as black spots within the stone.

CLOUD: A cluster of small inclusions, or internal flaws, within a diamond.

CROWN: The top of a diamond. Everything above the girdle.

CULET: The bottom facet of a diamond, usually very small.

DISPERSION: Colored light reflected from within a diamond; also called fire.

EYE-CLEAN: Refers to a diamond that has no inclusions or blemishes visible to the naked eye.

FACET: A polished surface on a diamond. A round, full-cut diamond usually has 58 facets.

FLUORESCENCE: A diamond’s reaction to ultraviolet (UV) light, causing the stone to glow in various colors.

FULL-CUT: A diamond with 58 or more facets.

GEMOLOGIST: A person who has been trained and accredited in diamonds and colored stones.

GIA: Gemological Institute of America, an independent, non-profit organization which sets and upholds standards for grading diamonds and other precious stones.

GIRDLE: The narrow, unpolished band around the widest part of the diamond; the girdle separates the crown and the pavilion of the stone.

HEAD: The prongs which hold a diamond in its setting.

INCLUSION: A flaw within a diamond, such as carbon spots or fractures.

KARAT: The measure of the purity of gold; 24-karat being pure gold. Jewelry is made from 18K and 14K gold, which contain other metals for strength.

LASER-DRILLED: A diamond that has been treated with a laser to remove carbon spots.

LOUPE: A small magnifying glass used to view gemstones

OFF-MAKE: A poorly proportioned diamond.

PAV: A method of setting diamonds very closely together, giving the illusion of one or more larger diamonds.

PAVILION: The bottom of a diamond; everything below the diamond’s girdle.

POINT: One-hundredth of a carat. A diamond weighing one-and-a-half carats weighs 150 points.

SEMI-MOUNT: A setting which is complete except for the main stone, which will be selected separately.

SINGLE-CUT: A diamond with only 16 or 17 facets.

SPARKLE: The liveliness of the light reflecting from a diamond; the sum of the brilliance and the fire (dispersion).

TIFFANY: A simple, elegant 2-3mm ring setting with a head that holds a single diamond.

by Fred Cuellar, author of the best-selling book “How to Buy a Diamond.” More questions? Ask the Diamond Guy
The founder and president of Diamond Cutters International, Fred Cuellar is one of the top diamond experts in the world, as well as a three-time Guinness Book record holder in jewelry design.
Fred Cuellar
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