Diameter ↔ weight (ct) – round brilliant
Approximate values for standard proportions. Actual weight may vary (depth/grind ±5–10%).
Smaller stones (melee)
| Diameter (mm) | Approx. weight (ct) |
|---|---|
| 1.0 | 0.005 |
| 1.1 | 0.0067 |
| 1.2 | 0.0075 |
| 1.25 | 0.0085 |
| 1.3 | 0.010 |
| 1.4 | 0.0125 |
| 1.5 | 0.015 |
| 1.6 | 0.018 |
| 1.7 | 0.021 |
| 1.8 | 0.025 |
| 1.9 | 0.030 |
| 2.0 | 0.035 |
| 2.1 | 0.040 |
| 2.2 | 0.045 |
| 2.3 | 0.050 |
| 2.4 | 0.055 |
| 2.5 | 0.060 |
| 2.6 | 0.065 |
| 2.7 | 0.070 |
| 2.8 | 0.080 |
| 2.9 | 0.090 |
| 3.0 | 0.100 |
Larger diamonds (solitaire and larger)
| Diameter (mm) | Weight approx. (ct) |
|---|---|
| 2.0 | 0.03–0.04 |
| 2.5 | ~0.06 |
| 3.0 | ~0.10 |
| 3.4 | ~0.15 |
| 3.8 | ~0.20 |
| 4.1 | ~0.25 |
| 4.4 | ~0.33 |
| 4.8 | ~0.40 |
| 5.1 | ~0.50 |
| 5.4 | ~0.60 |
| 5.7 | ~0.70 |
| 5.9 | ~0.80 |
| 6.2 | ~0.90 |
| 6.5 | ~1.00 |
| 6.9 | ~1.25 |
| 7.4 | ~1.50 |
| 7.8 | ~1.75 |
| 8.1 | ~2.00 |
| 8.7 | ~2.50 |
| 9.3 | ~3.00 |
| 9.8 | ~3.50 |
| 10.2 | ~4.00 |
| 11.1 | ~5.00 |
Tip: when pricing, we always work with real data from the certificate (diameter, depth, weight in ct).
