Carat Weights
What does the unit carat represent?
Interestingly enough, it is the weight of one carab seed, a product of the locust tree. These seeds are nearly uniform in weight and therefore were used by early gem traders as a unit of weight by which to measure their diamonds.

This is a chart that explains the range of acceptable carat weights (points) used in our fractional descriptions. Since no two diamonds are exactly alike, diamond carat weights must fall within the decimal range listed in this chart for specific fractional descriptions to be used to describe the weight of diamonds in a particular piece of our jewelry.