All diamonds are rare and no two diamonds are alike. A diamond’s quality and rarity is determined by its unique combination of characteristics of Color, Cut, Clarity and Carat Weight. The International Diamond Grading System™, used around the world since its invention by GIA in the 1950s, is based on the Four Cs.
• Carat: Diamonds are weighed in metric carats. Two carats weight about the same as a small paper clip. A carat is divided into 100 “points”, so a diamond of 50 points weighs 0.50 carats.
• Clarity: Nearly all diamonds contain unique clarity characteristics. Flawless diamonds are exceptional and costly. Most inclusions are invisible unless magnified.
• Color: Colorless diamonds are extremely uncommon. Most diamonds have a slight yellow or brown tint. GIA uses letters to represent colors, beginning with D (colorless) and ending at Z (light yellow or brown). “Fancy colored diamonds” come in every color imaginable, are also very unusual and have their own GIA color grading system.
• Cut: While diamonds come in different shapes, such as round, pear or marquise, the term “cut” refers to proportion. The well-cut, balanced diamond has unbridled brilliance, sparkle and fire.
Below is a suite of diamonds including, (clockwise from top) Asscher cut, pear shape, marquise shape and round brilliant cut. These diamond shapes remain popular in today’s diamond market. Photo by Robert Weldon, © GIA 2008
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