Carat

The weight of a diamond is measured in carats. One carat is divided into 100 points, so a diamond of 25 points is described as a quarter of a carat or 0.25 carats. The larger the diamond, and therefore the rarer, the more expensive per carat it will be. For example, a 1ct diamond costs much more than a 1/2ct diamond and one 30 point diamond costs much more than 30 one point diamonds.

The carat measurement of a diamond is actually the diamond's weight rather than its size or diameter. This is important to remember as depending upon the proportions of the cut of the diamond, some diamonds may appear to have a larger top surface area (table) than an ideal cut diamond, but the diamonds may be of the same carat weight. Diamonds are sometimes cut in shallow proportions to make a diamond look bigger but this sacrifices the brilliance and life of diamonds, and makes them less valuable.

The weight of a diamond is always expressed in carats, one carat equals 200 milligrams. This is further broken down into points - 100 points equals one carat.

A diamond's weight is always recorded to 2 decimal places in carats, or as the number of points. For example, a half-carat stone can be described as 0.50ct or 50 points.