Because
of the variations in browser settings, screen resolutions and monitor
variations; accurately showing sizes on a screen is impossible.Find a template with calibrated holes .. then you can make the following estimates. If you want to use circle sizes where the diamer is printed, make sure you know whether the measurement is the outside or inside of the circle.
| Diameter - mm | Weight - ct |
| 2.2 | 0.04 |
| 3.0 | 0.10 |
| 4.1 | 0.25 |
| 5.2 | 0.50 |
| 6.5 | 1.00 |
| 7.4 | 1.50 |
| 8.2 | 2.00 |
| 9.0 | 2.50 |
| 9.3 | 3.00 |
| 11.0 | 5.00 |
For other diameters use the formula
Weight in carats = diameter² x depth x 0.0061
If you cannot measure the depth but the diamond is well proportioned
Weight in carats = diameter³ x 0.0037
All measurements assumed to be in millimeters