What is a karat?

Diamond carat weight measures how much a diamond weighs. A metric “carat” is defined as 200 milligrams. Each carat is subdivided into 100 ‘points.’ In the presence of a jeweler, this weight may describe a diamond below one carat by it’s points. A jeweler may refer to a diamond that weighs 0.45 carats as a ‘forty-five pointer.’ Diamond weights greater than one carat are usually described in carats and decimals, such as 1.04.