Diamonds are measured in carat weight, with each carat equaling 100 points. For example, a 0.75 carat diamond is the same as a 75-point diamond or a 3/4 carat stone. The carat weight, or mass, of the diamond is an important determiner of value. The larger the diamond, the more rare it is, therefore, the more valuable.
Carat weight, while important, is only one aspect of value. A large stone holds little value if it lacks brilliance, purity and the proper cut.
Diamond Weight Tolerances
U.S. law allows a half-point tolerance measured to a carat (0.001) and rounded to the nearest hundredth (0.01). Example: 0.995 carat can legally be described and sold as a one-carat diamond in the United States. International trade and G.I.A.'s GemTrade round up to the next higher hundredth only from nine thousandths of a carat. Example: 0.999 carat = 1.00 carat, 0.998 carat = 0.99 carat.