Carat Weight

Besides colour, clarity and cut, carat weight provides a further basis in the valuation of a diamond. The weight of all gemstones is measured in carats. There are 142 carats to an ounce. Each carat contains 100 points.

5 carat= 1.00 gram
1 carat = 1.00 [100 points]
1/2 carat = 0.50 [50 points]

The weight of a diamond is to be indicated to the second decimal point. The international abbreviation is - ct.

Diamond weight is determined by an extremely sensitive scale or diamond balance. It is possible to determine a round brilliant cut diamond's weight by measuring its proportions. This latter method is not nearly as accurate as using a proper scale.

Calculating the Weight of Diamonds

Within certain tolerances, the brilliant is a standardized form of cut polished with certain well established sizes of facets and angles, so there is a definite relationship between weight and size of a brilliant. It is therefore possible to estimate the size of a brilliant from its weight and vice versa. This also applies to the fancy cuts.

The standardized forms of cut and the relative constant specific gravity of 3.52 enable one to calculate the weight of a diamond by establishing the volume.

With today's usual brilliant cut with flat crown, fine girdle and a total height of 58-62%, the following formula is used:

Carat weight = height x diameter [squared] x 0.0061

Example:

Girdle diameter - 10.0mm
Total height - 6.0mm
Carat weight = 6.0 x 10.0[squared] x 0.0061 = 3.66ct.