Because diamonds are so valuable, it’s essential to have a universal grading system for comparing their quality. In the 1940s and ’50s, GIA developed the 4Cs and the GIA International Diamond Grading System™ to objectively compare and evaluate diamonds.

Carat Color Clarity Cut Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip. (Don’t confuse carat with karat, as in “18K gold,” which refers to gold purity.) Just as a dollar is divided into 100 pennies, a carat is divided into 100 points. For example, a 50-point diamond weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on the other members of the Four C’s: clarity, color and cut. The majority of diamonds used in fine jewelry weigh one carat or less.

Because even a fraction of a carat can make a considerable difference in cost, precision is crucial. In the diamond industry, weight is often measured to the hundred thousandths of a carat, and rounded to a  hundredth of a carat.  Diamond weights greater than one carat are expressed in carats and decimals. (For instance, a 1.08 ct. stone would be described as “one point oh eight carats,” or “one oh eight.”)How did the carat system start? The carat, the standard unit of weight for diamonds and other gemstones, takes its name from the carob seed. Because these small seeds had a fairly uniform weight, early gem traders used them as counterweights in their balance scales. The modern metric carat, equal to 0.2 grams, was adopted by the United States in 1913 and other countries soon after. Today, a carat weighs exactly the same in every corner of the world. Beautiful and rare, diamonds are desired for their sparkle and message of love. When you buy a diamond there are four points that you should consider, collectively known as the Four C’s.

Cut:
Refers to the symmetry and proportions of the stone; it is what gives the diamond its sparkle. There are many diamond shapes to choose from. Whatever shape and quality you prefer, a Laboratory Report should be a requirement for your engagement ring or any significant diamond purchase.

Color:
The most desirable diamonds are colorless. The best color is D, which is almost clear white; the color scale descends from there through the alphabet toward Z, moving further away from colorless toward yellow or brown tints.

Clarity:
Diamonds have small imperfections in them known as inclusions; the fewer inclusions, the more valuable the stone.

Carat Weight:
This is the size of the stone. The word carat comes from the carob seeds that were used to balance scales in ancient times.