Diamond Size Guides
Wondering what a 1 carat round diamond looks link on a hand? Our round diamond size chart will help you convert millimeter (mm) size to carat size for round cut diamonds.
Round Diamond Sizes
| Round MM Size |
Round Weight (ct) |
Black Diamond ct weight (Approx) |
|---|---|---|
| 0.8 mm. | 0.00 | 0.00 |
| 1 mm. | 0.01 | 0.01 |
| 1.1 mm. | 0.01 | 0.01 |
| 1.2 mm. | 0.01 | 0.01 |
| 1.25 mm. | 0.01 | 0.01 |
| 1.3 mm. | 0.01 | 0.01 |
| 1.5 mm. | 0.02 | 0.02 |
| 1.75 mm. | 0.02 | 0.02 |
| 1.8 mm. | 0.03 | 0.03 |
| 2 mm. | 0.03 | 0.04 |
| 2.2 mm. | 0.04 | 0.05 |
| 2.5 mm. | 0.06 | 0.07 |
| 2.75 mm. | 0.08 | 0.10 |
| 3 mm. | 0.10 | 0.12 |
| 3.25 mm. | 0.14 | 0.17 |
| 3.5 mm. | 0.17 | 0.20 |
| 3.75 mm. | 0.21 | 0.25 |
| 4 mm. | 0.25 | 0.33 |
| 4.25 mm. | 0.28 | 0.36 |
| 4.5 mm. | 0.36 | 0.47 |
| 4.75 mm. | 0.44 | 0.57 |
| 5.0 mm. | 0.50 | 0.65 |
| 5.25 mm. | 0.56 | 0.73 |
| 5.5 mm. | 0.66 | 0.89 |
| 5.75 mm. | 0.75 | 1.01 |
| 6 mm. | 0.84 | 1.20 |
| 6.25 mm. | 0.93 | 1.30 |
| 6.5 mm. | 1.00 | 1.40 |
| 6.8 mm. | 1.25 | 1.80 |
| Round MM Size |
Round Weight (ct) |
Black Diamond ct weight (Approx) |
|---|---|---|
| 7 mm. | 1.30 | 1.90 |
| 7.3 mm. | 1.50 | 2.10 |
| 7.5 mm. | 1.67 | 2.40 |
| 7.75 mm. | 1.75 | 2.50 |
| 8 mm. | 2.00 | 2.80 |
| 8.25 mm. | 2.11 | 3.00 |
| 8.5 mm. | 2.43 | 3.50 |
| 8.7 mm. | 2.50 | 3.50 |
| 9 mm. | 2.75 | 3.90 |
| 9.1 mm. | 3.00 | 4.20 |
| 9.5 mm. | 3.35 | 4.70 |
| 9.75 mm. | 3.61 | 5.10 |
| 10 mm. | 3.87 | 5.50 |
| 10.25 mm. | 4.16 | 5.50 |
| 10.5 mm. | 4.41 | 5.80 |
| 10.75 mm. | 4.57 | 6.00 |
| 11 mm. | 4.91 | 6.40 |
| 11.25 mm. | 5.49 | 7.20 |
| 11.5 mm. | 5.85 | 7.70 |
| 12 mm. | 6.84 | 8.90 |
| 12.25 mm. | 7.26 | 9.50 |
| 12.5 mm. | 7.36 | 9.60 |
| 12.75 mm. | 7.52 | 9.80 |
| 13 mm. | 8.51 | 11.10 |
| 13.5 mm. | 9.53 | 12.40 |
| 14 mm. | 10.49 | 13.70 |
| 15 mm. | 12.89 | 16.80 |
| 16 mm. | 16.06 | 20.90 |
