Diamond Carat Weight

Quite simply, a diamond’s carat is a measurement of weight. One carat equals 1/5 of 1 gram (or 200 milligrams) and is based on 100 points, meaning .50 is a half-carat, .25 a quarter-carat etc.

Diamond carat weight is often associated with size, which does not always coincide, considering size is determined by the millimeter measurement across the top, which doesn’t take into the weight difference that comes from the cut type and the cut grade – which affect both shape and sparkle. Cut should always be taken into consideration when looking at a diamond’s carat weight. For example a diamond with a poor cut, may hide much of its carat weight in the base, appearing much smaller. Conversely, a diamond that is well cut, but a lower carat weight, may appear much larger.

Carat Weight Scale

A few gems of wisdom:

• Although diamond carat weight influences cost quite a bit, when determining diamond size, always consider the distance in millimeters across the top (as that is how diamonds are presented when set in a ring), as well as the cut grade.
• If sparkle is more important, start with cut, color, and clarity first before choosing a carat weight.
• If size is more important, and budget is a concern, consider a stone with a higher diamond carat size and lower clarity and/or color rating.
• Consider “under sizes” which are diamonds that weigh just below the full and half carat weights. They represent a very good value, as small size differences are hard to visually detect.

View and print our Diamond Carat Size Guide.