Within certain tolerances the brilliant is a standardized form of cut, which is polished with certain well-established sizes of facets and angles, so that 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 following tables show the relationship between carat weight and size of cut diamonds in the accepted forms. The figures are taken from the weight tables obtainable with a LEVERIDGE-Gauge.
Eight-cut diamonds
| Girdle diameter in mm | ct-weight | stones per carat |
| 0.9 | - | 240 |
| 1.0 | - | 200 |
| 1.1 | - | 155 |
| 1.2 | - | 125 |
| 1.3 | 0.01 | 100 |
| 1.4 | - | 85 |
| 1.5 | - | 73 |
| 1.6 | - | 58 |
| 1.7 | 0.02 | 48 |
| 1.8 | - | 40 |
| 1.9 | - | 33 |
| 2.0 | 0.03 | 30 |
Note: These weights refer to stones with a small girdle. For stones with medium to thicker girdles 5-10 % of the weight should be added.
Carré diamonds
| Girdle diameter in mm | ct-weight | stones per carat |
| 1.3 | 0.02 | 53 |
| 1.4 | - | 44 |
| 1.5 | - | 40 |
| 1.6 | 0.03 | 33 |
| 1.7 | 0.04 | 25 |
| 1.8 | - | 23 |
| 1.9 | 005 | 20 |
| 2.0 | - | 18 |
| 2.1 | 0.06 | 16 |
| 2.2 | 0.07 | 13 |
| 2.3 | 0.08 | 12 |
| 2.4 | 0.09 | 11 |
| 25 | 0.10 | 10 |
| 2.6 | 0.11 | 9 |
| 2.7 | 0.12 | 8 |
| 2.8 | 0.13 | 7 1/2 |
| 2.9 | 0.14 | 7 |
| 3.0 | 0.15 | 6 1/2 |
Note: Weight formula to be used for larger stones. The above weights refer to carré diamonds with flat crown. For stones with higher crown 10-20 % must be added to given carat weight.
Full cut diamonds
smallest to melée brilliants
| Girdle diameter in mm | ct weight | stones per carat |
| 1 . Smallest brilliants | ||
| 1.7 | 0.02 | 50 |
| 1.8 | 40 | |
| 1.9 | 37 | |
| 2.0 | 0.03 | 33 |
| 2.1 | 29 | |
| 2. Small brilliants | ||
| 2.2 | 0.04 | 25 |
| 2.3 | 22 | |
| 2.4 | 0.05 | 20 |
| 2.5 | 18 | |
| 2.6 | 0.06 | 16 |
| 3. Melee brilliants | ||
| 2.7 | 0.07 | 14 |
| 2.8 | 0.98 | 12 |
| 2.9 | 0.09 | 11 |
| 3.0 | 0.10 | 10 |
| 3.1 | 0.11 | 9 |
| 3.2 | 0.12 | 8 |
| 3.3 | 0.14 | 7 |
Note: These weights refer to stones with small girdle. Add 5-10% to the weight for medium and thick girdles.
Full cut brilliants
Larger stones
| Girdle diameter in mm | height in mm (60 % of girdle diameter incl. small girdle) | ct weight of stone |
| 3.1 | 1.86 | 0.11 |
| 3.2 | 1.92 | 0.125 |
| 3.3 | 1.98 | 0.14 |
| 3.4 | 2.04 | 0.15 |
| 3.5 | 2.10 | 0.16 |
| 3.6 | 2.16 | 0.17 |
| 3.7 | 2.22 | 0.18 |
| 3.8 | 2.28 | 0.20 |
| 3.9 | 2.34 | 0.22 |
| 4.0 | 2.40 | 0.23 |
| 4.2 | 2.52 | 0.25 |
| 4.4 | 2.64 | 0.28 |
| 4.6 | 2.76 | 0.33 |
| 4.8 | 2.88 | 0.38 |
| 5.0 | 3.00 | 0.46 |
| 5.2 | 3.12 | 0.50 |
| 5.4 | 3.24 | 0.57 |
| 5.6 | 3.36 | 0.64 |
| 5.8 | 3.48 | 0.71 |
| 6.0 | 3.60 | 0.79 |
| 6.2 | 3.72 | 0.87 |
| 6.4 | 3.84 | 0.96 |
| 6.6 | 3.96 | 1.05 |
| 6.8 | 4.08 | 1.15 |
| 7.0 | 4.20 | 1.26 |
| 7.2 | 4.32 | 1.36 |
| 7.4 | 4.44 | 1.49 |
| 7.6 | 4.56 | 1.61 |
| 7.8 | 4.68 | 1.74 |
| 8.0 | 4.80 | 1.88 |
| 8.2 | 4.92 | 2.02 |
| 8.4 | 5.04 | 2.17 |
| 8.6 | 5.16 | 2.33 |
| 8.8 | 5.28 | 2.50 |
| 9.0 | 5.40 | 2.67 |
| 9.2 | 5.52 | 2.86 |
| 9.4 | 5.64 | 3.05 |
| 9.6 | 5.76 | 3.25 |
| 9.8 | 5.88 | 3.45 |
| 10.0 | 6.00 | 3.67 |
| 10.2 | 6.12 | 3.89 |
| 10.4 | 6.24 | 4.13 |
| 10.6 | 6.36 | 4.37 |
| 10.8 | 6.48 | 4.63 |
| 11.0 | 6.60 | 4.90 |
Note: These figures refer to brilliants of a total height of ca. 60 % inclusive a normal small girdle of about 2-3 % of the girdle diameter.
In the case of very thick or very small girdles and in the case of brilliants with extremely flat crown and pavilion or very high proportions about 1 -5 % of the given carat weight should be added or subtracted.
| Weighing | Formula for Calculating the Weight |