Carat is often confused with size even though it is actually a measure of weight. One carat is equivalent to 200 milligrams. One carat can also be divided into 100 points. A .75 carat diamond is the same as a 75-points or 3/4 carat diamond.

A 1 - carat diamond costs exactly twice the price of a half-carat diamond, right? Wrong. Since larger diamonds are found less frequently in nature, which places them at the rarest level of the Diamond Quality Pyramid, a 1 - carat diamond will cost two times more than a 1/2 - carat diamond (assuming color, clarity and cut remain constant).