For many persons it is not easy to see the relationship between the carat weight of the diamond and its dimensions in millimeters.

For the definition of the weight of the diamond we invite you to consult this page which explains all about the carat.

Point

The weight of a diamond can also be expressed in "points". 100 points equivalent to a 1 carat diamond. It is therefore only a multiplying factor of 100.

The point is often used by jewelers to characterize the weight of small diamonds. Thus 10 points refer to a diamond of 0.1 carat, 55 points to a diamond of 0.55 carat.

The influence of the shape of the diamond

Expressing the ratio between the carat weight of a diamond and its dimensions in mm can only be an approximate information. Indeed, the dimensions in millimeters will depend, among others, on the shape of the diamond.

It is obvious that, at equal weight, a diamond of a round shape will not have the same dimensions as a diamond cut in emerald or heart shapes. Simple affair of proportions and also of visual effect.

Proportions

In addition to the shape of the diamond the proportions also affect its dimensions in millimeters .

Thus for a round diamond, according to the criteria of ideal sizes, the total depth can vary from 59 to 63%

It is obvious that 2 round diamonds of one carat with a depth of respectively 63% and 59% will not have the same diameter.

Ratio between carat weight and size in mm of a round diamond

The data below are therefore relative and give the reports for a round diamond cut in the same way. The higher the weight of the diamond, the more the shape of the size may have an influence on the dimensions of the stone.

Evolution of the weight / diameter ratio of a round diamond

This table and accompanying graph give the evolution of the diameter in mm of a round diamond compared to its weight in carat.

Carats	Points	Millimeters
0,006	0,6	1
0,007	0,7	1,1
0,009	0,9	1,2
0,01	1	1,3
0,013	1,3	1,4
0,015	1,5	1,5
0,018	1,8	1,6
0,02	2	1,7
0,025	2,5	1,8
0,03	3	1,9	Make a click on the picture to zoom
0,035	3,5	2
0,04	4	2,1
0,045	4,5	2,2
0,05	5	2,3
0,06	6	2,4
0,065	6,5	2,5
0,07	7	2,6
0,08	8	2,7
0,09	9	2,8
0,1	10	2,9
0,11	11	3
0,16	16	3,5
0,26	26	4
0,36	36	4,5
0,59	59	5
0,64	64	5,5
0,8	80	6
1,05	105	6,5