Carat is a unit for mass which is used for gemstones. The word stems from the Greek keration (fruit of the carob tree) and has found its way into the English language via Arabic and Italian.

Carob seed
Different countries used to have their own carat, approximately equal to the weight of a carob tree seed. Because of their constant weight, these seeds were used on precision balances. But in 1907 the metric carat was established as 200 milligrams.

The Coster Diamonds Valuation report describes the carat weight exactly up to 100th of the total carat. Each carat is divided into 100 so-called points. One 1-carat diamond has 100 points, a ¾-carat diamond has 75 points et cetera. The points total is determined in a quantity of units. A ¾-carat diamond may consist of, say, 69 and 82 points.