DIAMOND GRADING TERMINOLOGY

A diamond's cost is based on the characteristics known as the "4 C's". Clarity, Color, and Cut (proportion) are the quality elements that together with the Carat Weight determine the value of a stone. The closer a diamond grades to the left of one or all of these scales the rarer and the more costly it will be. While clarity is frequently assumed to be the most important factor of all the "C's", in fact, color and cut have a more profound effect on the visual appearance of a diamond.

CARAT WEIGHT

Carat is the unit of weight for all gemstones. One carat is subdivided into 100 "points". Therefore a diamond measuring 75 points is 3/4 carat in weight or 0.75ct. There are five carats in a gram. The word "carat" comes from the seed of the carob tree pod which is found in tropical climates. These seeds were used until this century to weigh precious gems.

CLARITY

A diamond's clarity is determined by the number, nature, position, size, and color of internal characteristics called "inclusions" and surface features called "blemishes." These irregularities occur in the liquid Magna (volcanic rock) within which the diamond was created. Diamonds are mostly pure carbon; however, during crystallization, other minerals nearby or even other bits of carbon forming more quickly may have become trapped within the cooling mass. These show themselves as the various characteristics that make up a diamond's clarity (including crystals, feathers, clouds, etc). Clarity is measured on a scale ranging from pure (flawless) to heavily included (I-3). A diamond's clarity is graded using 10X magnification under good lighting by an experienced grader. The final clarity grade is usually determined by how easy the inclusions and blemishes are for the grader to see.

COLOR

Ideally, a diamond should have no color at all, like a drop of spring water. Increasing degrees of body color is measured on a scale ranging from no color at all (D) to deeply colored (Z). Beyond "Z" is the range where the diamond's color is vivid and rich, called "fancy colors." Diamonds of known color are used as comparison stones for color grading. Grading is done by comparing the diamond to be graded against these "master stones" under either artificial or natural north daylight ( in the Northern Hemisphere). A machine called the "Colorimeter" can be used for color grading, however, there is no substitute for the trained human eye.

CUT

Cut, sometimes the forgotten "C," ensures that a given stone has maximum brilliance and sparkle which would not be the case were the stone cut for weight alone. We use the following scale to grade a stone on its overall appearance. Simply put, when looking at a diamond, if it doesn't catch your eye or if it doesn't flash in the light, it's probably not well-cut. Good cutting is what brings fire to the ice.

LAB-GROWN DIAMONDS

Learn more about Lab-Grown Diamonds from GIA.