Why Diameter is Often a Surer Measure of a Diamond than Size
For instance, imagine buying a giant diamond orbit ring and then bringing it home. Looking at it under the living room light, you realize that it lacks the kind of fire and shine of one would expect form something so big.
This is what can often come of focusing solely on the size of a gem you plan on buying. An unscrupulous diamond cutter would normally compromise on a variety of factors to make the stone look bigger. The girdle could be made thicker, the crown steeper, and many other proportions oriented to make the diamond look chubbier. The problem though is that such a stone has little of the luster and fire it could have. A diamond cutter like this essentially trades in that bit of “magic” for size.
An expertly cut diamond weighing 1 carat should have a diameter of around 6.4 mm, and it is smart to watch for this instead of the fatness of the stone. Steer clear of the cheaper “gems” and get yourself something actually worth what you are paying.