Weight measurement used in measuring the size of a gemstone. A carat is 0.2 grams, or 200 milligrams. (The carat weight system is used worldwide, even in the United States where the metric system isn't used.) A point is a weight measurement used only by very small, precious gemstones such as Diamonds, and represents 1/100th of a carat.
The abbreviation for carat is ct.
The term carat should not be confused with karat which is used to measure Gold quality.