A Guide to Compare Diamond Carat Weight to mm Size
Use this guide to compare a diamond's carat weight to its approximate top dimensions. Please note this is only a rough guide as the weight of the stone will vary depending upon its depth.
In the case of brilliant cut diamonds, the millimetre value refers to the stone's diameter. For princess cut diamonds, the millimetre value means that dimension square.
| Brilliant Cut | Princess Cut | Marquise Cut | Oval Cut | Pear Shaped | Emerald Cut | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.06-0.08cts | = | 2.5mm | 0.06-0.08cts | = | 2.1-2.2mm | 0.07ct | = | 4X2mm | 0.15-0.18ct | = | 4X3mm | 0.15-0.18ct | = | 4.5X3mm | 0.25ct | = | 4X3mm | ||||||
| 0.10-0.12cts | = | 3mm | 0.10-0.12cts | = | 2.5-2.7mm | 0.15ct | = | 5X2mm | 0.25ct | = | 5X3mm | 0.25ct | = | 5X3.5mm | 0.35ct | = | 5X3mm | ||||||
| 0.16-0.18cts | = | 3.5mm | 0.16-0.18cts | = | 3mm | 0.20ct | = | 5X3mm | 0.40ct | = | 5X4mm | 0.35ct | = | 5.75X4mm | 0.40ct | = | 5X3.5mm | ||||||
| 0.20-0.22cts | = | 3.8mm | 0.20-0.22cts | = | 3.2-3.3mm | 0.25ct | = | 6X3mm | 0.50ct | = | 6X4.5mm | 0.40ct | = | 6X4mm | 0.50ct | = | 5X4mm | ||||||
| 0.24-0.26cts | = | 4mm | 0.24-0.26cts | = | 3.4-3.5mm | 0.35ct | = | 6.5X3.5mm | 0.65ct | = | 6.5X4.5mm | 0.50ct | = | 6.5X4.5mm | 0.60ct | = | 6X3mm | ||||||
| 0.27-0.29cts | = | 4.2mm | 0.27-0.29cts | = | 3.5mm | 0.35ct | = | 7X3mm | 0.75ct | = | 7X5mm | 0.75ct | = | 7X5mm | 0.70ct | = | 6X4mm | ||||||
| 0.30-0.35cts | = | 4.5mm | 0.30-0.35cts | = | 3.8-3.9mm | 0.40ct | = | 6.5X4mm | 1.00ct | = | 7.5X5.5mm | 1.00ct | = | 8X5mm | 0.80ct | = | 6.5X4.5mm | ||||||
| 0.36-0.38cts | = | 4.6mm | 0.36-0.38cts | = | 3.8-3.9mm | 0.50ct | = | 7X4.5mm | 1.25ct | = | 8X6mm | 1.50ct | = | 9X6mm | 0.95ct | = | 7X4mm | ||||||
| 0.39-0.43cts | = | 4.7-4.8mm | 0.39-0.43cts | = | 3.9-4.1mm | 0.70ct | = | 8X5mm | 1.50ct | = | 8.5X6.5mm | 1.00ct | = | 7X5mm | |||||||||
| 0.44-0.47cts | = | 4.8-4.9mm | 0.44-0.47cts | = | 4.1-4.3mm | 0.70ct | = | 9X4mm | 1.75ct | = | 9X6mm | 1.25ct | = | 7.5X5.5mm | |||||||||
| 0.48-0.52cts | = | 5mm | 0.48-0.52cts | = | 4.3-4.5mm | 0.75ct | = | 9X4.5mm | 2.00ct | = | 9X6mm | 1.50ct | = | 8X5mm | |||||||||
| 0.53-0.59ctsct | = | 5.2mm | 0.53-0.59ctsct | = | 4.6mm | 0.80ct | = | 9X5mm | 2.00ct | = | 8.5X6.5mm | ||||||||||||
| 0.60-0.62cts | = | 5.3-5.4mm | 0.60-0.62cts | = | 4.7mm | 1.00ct | = | 9X6mm | 2.25ct | = | 9X6mm | ||||||||||||
| 0.63-0.68ctsct | = | 5.5-5.6mm | 0.63-0.68ctsct | = | 4.8mm | 2.50ct | = | 9X7mm | |||||||||||||||
| 0.69-0.74cts | = | 5.6-5.8mm | 0.69-0.74cts | = | 4.8-4.9mm | ||||||||||||||||||
| 0.75-0.80cts | = | 5.9-6mm | 0.75-0.80cts | = | 4.9-5mm | ||||||||||||||||||
| 0.90-0.92cts | = | 6.2-6.3mm | 0.90-0.92cts | = | 5.1-5.2mm | ||||||||||||||||||
| 0.93cts-0.99cts | = | 6.3-6.4mm | 0.93cts-0.99cts | = | 5.2-5.3mm | ||||||||||||||||||
| 1.0cts-1.05cts | = | 6.4-6.5mm | 1.0cts-1.05cts | = | 5.3-5.5mm | ||||||||||||||||||
| Approx 1.1cts | = | 6.6mm | Approx 1.1cts | = | 5.8mm | ||||||||||||||||||
| Approx 1.25cts | = | 6.8-6.9mm | Approx 1.25cts | = | 6mm | ||||||||||||||||||
| Approx 1.3cts | = | 7mm | Approx 1.3cts | = | 6.1mm | ||||||||||||||||||
| Approx 1.4cts | = | 7.2-7.3mm | Approx 1.4cts | = | 6.2mm | ||||||||||||||||||
| Approx 1.5cts | = | 7.5mm | Approx 1.5cts | = | 6.4mm | ||||||||||||||||||
| Approx 1.75cts | = | 7.7-7.8mm | Approx 1.75cts | = | 6.6-6.8mm | ||||||||||||||||||
| Approx 2cts | = | 8-8.2mm | Approx 2cts | = | 7mm | ||||||||||||||||||