Diamond Carat
Understanding Diamond Weight and Size

Carat (ct.) is the standard unit of measurement used to determine the weight of a diamond. One carat is equal to 0.2 grams, about the same weight as a paperclip. Each carat can be subdivided into 100 points. For example, a 0.75 carat diamond may be referred to as a 75-point diamond.

The word "carat" comes from the carob seed. These small seeds had a fairly uniform weight and were originally used by ancient traders 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.

Size vs. Weight

Although carat is a measure of a diamond's weight, there is a correlation between a diamond's weight and its visual size. However, two diamonds of equal carat weight can appear different in size based on:

• The cut and shape of the diamond
• How the weight is distributed
• How deep or shallow the cut is
• The diameter of the diamond

Price and Carat Weight

As diamond carat weight increases, the price per carat increases at an accelerated rate. This is because larger diamonds are more rare and more desirable. For example, a 2-carat diamond of the same quality costs more than twice the price of two 1-carat diamonds.

When choosing a diamond, remember that carat weight is just one of the 4Cs. A smaller diamond with excellent cut, color, and clarity can appear more brilliant and beautiful than a larger diamond of lower quality.