One carat equals 200mg or 1/5 of a gram or 3-1/16 grains. One pennyweight contains approximately 7.9 carats. Since different stones may be more or less dense, a one-carat stone will differ in size depending on the type of stone. The carat weight of a diamond is divided into 100 parts or points, thus a fifty-point diamond is equal to 1/2 of a carat and a twenty-five point diamond equals 1/4 of a carat. The carat is a unit of weight and not related to the term karat as used as a unit of the fineness or purity of gold. Refer to the ''Faceted Gemstone Weight and Size Charts'' for specific stone information.