REFERENCE
Carat size chart
Approximate face-up millimeter dimensions for well-cut stones, by shape. Individual stones vary a little with their exact proportions.
| Weight | Round (mm) | Oval | Princess | Cushion | Emerald | Pear |
|---|---|---|---|---|---|---|
| 0.50 ct | 5.1 | 6.1 x 4.4 | 4.4 | 4.7 x 4.5 | 5.5 x 3.8 | 6.7 x 4.4 |
| 0.75 ct | 5.9 | 7.0 x 5.1 | 5.0 | 5.4 x 5.1 | 6.3 x 4.4 | 7.7 x 5.1 |
| 1.00 ct | 6.5 | 7.7 x 5.6 | 5.5 | 6.0 x 5.7 | 7.0 x 4.8 | 8.5 x 5.6 |
| 1.25 ct | 6.9 | 8.3 x 6.0 | 6.0 | 6.4 x 6.1 | 7.5 x 5.2 | 9.2 x 6.0 |
| 1.50 ct | 7.4 | 8.8 x 6.4 | 6.4 | 6.8 x 6.5 | 8.0 x 5.5 | 9.7 x 6.4 |
| 2.00 ct | 8.1 | 9.7 x 7.1 | 7.0 | 7.5 x 7.1 | 8.8 x 6.0 | 10.7 x 7.1 |
| 2.50 ct | 8.8 | 10.5 x 7.6 | 7.5 | 8.1 x 7.7 | 9.4 x 6.5 | 11.5 x 7.6 |
| 3.00 ct | 9.3 | 11.1 x 8.1 | 8.0 | 8.6 x 8.1 | 10.0 x 6.9 | 12.3 x 8.1 |
Reading the chart like a buyer
- Size grows with the cube root of weight: the jump from 1.0 to 2.0 carats adds about a quarter to the diameter, not double.
- Elongated shapes read bigger than their weight; depth-heavy shapes read smaller.
- Two stones of equal weight can face up noticeably different; the millimeter line on the report outranks the carat line for looks.
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