Diamond weight is expressed in carats (one carat is equal to 200 milligrams). Carats are divided into 100 points so a 0.78 ct diamond is called a 78 pointer. Another term used by diamond professionals is grain. One grain equals 25 points so a one-carat diamond can be called 1ct, or 100 points, or 4 grains.
Cut influences Carat Weight
Diamonds that weigh the same may not have the same vertical spread, depending on how they were cut. Those cut too shallow or too deep will look small for their weight and/or have poor light performance.
The goal of most cutters is to maximize carat weight from pieces of rough. This means many diamonds are cut too shallow or deep. A diamond’s grading report lists its measurements in millimeters. The first two numbers are min and max spread; be sure the diamond has appropriate spread for carat weight. Even then one is not assured of the critical angles necessary for high performance.