Diamonds. Diamond carat weight is the measurement of how much a diamond weighs. Diamond price increases with carat weight, because larger diamonds are more rare. Learn how diamond carat weight affects size and price. Compare actual size diamonds of different carat weights using a printable size chart. Diamonds are sold by the carat (shown as ct.), which is actually a unit of weight, though most think of a carat in terms of size. The word “carat” comes from the “carob” seed, the original unit of measure for diamond traders. Today, a carat is equal to exactly 0.2 grams (about the weight of a paper clip). Carat weight is unrelated to the similar sounding karat, which refers to gold’s purity.
Among the 4 Cs, the most determining factor is without a doubt the cut of the diamond – its symmetry, its balance – neither too high, nor too flat. It is the guarantee of exceptional beauty. Central brilliant-cut Cartier diamonds whose size is greater than 0.30 carats on the GIA scale are classified “Very Good” or “Excellent”*, guaranteeing them an optimal brilliance and a unique sparkle.
Several additional criteria imposed by our “Cartier Diamond Experts” for brilliant-cut diamonds:
- the table must be between 56% and 63% for diamonds over 0.23 carats;
- the total depth must be between 58% and 63% without the culet;
- the girdle must be from slightly thick to thick.
*For brilliant-cut center diamonds under 0.30 ct, as well as for fancy-cut center diamonds, the Cut grade accepted by Cartier is between “Good” and “Excellent”.
The unit of measurement of diamond weight is the carat; its name comes from the carob seed that was once used to weigh diamonds. The weight is the most important criteria in determining the price of a diamond. A carat corresponds to 0.20 g.