A carat is a unit of weight used for gemstones, first introduced in 1907. One carat is equal to 200 milligrams. 1/100th of a carat is called a 'point'. Using this system, a 0.50 carat gemstone may be called a one-half carat stone or a 50-point stone. 'Carat' and 'karat' do not have the same meaning. Karat refers to the percentage of gold in an item, not to its weight.
Carat - Definition 
