Diamond Carat Weight Diamonds are measured in metric carat (ct), the standard unit of weight for diamonds, which equals 0.20 grams or 1/142 of an ounce. Carats are divided into points with each point representing 1/100th of a carat. A 1.00ct diamond is also represented as 100 points. A 0.75ct is also represented as 75 points. The most obvious distinguishing appeal of a diamond is the carat weight of it and it’s not the most important aspect in determining the value of a diamond, it may be the least important factor in some cases. The carat measures the actual weight of the diamond and not the size. Diamonds that are the same size may alter the exact carat weight. It is known that diamonds of the same proportion, a larger diamond would be more valuable then a smaller diamond. A metric carat can be expressed in different measurements. For example, a one carat diamond can be expressed as: Ø 1 carat Ø 0.20 gram Ø 1/5 gram Ø 200 milligrams Ø 100 points Ø 4 grainer The following table gives you an approximate guide to diamond sizes in millimeters (mm) with approximate carat weight. The numbers displayed under carat weight are approximate carat weights and the numbers displayed under the diamond shapes are approximate millimeters. Carat Weight | Round | Princess | Emerald | Oval | Pear | Marquise | Heart | Trillion | | 0.25 | 4.1 | 3.5 x 3.5 | 5 x 3 | 5 x 3 | 5.5 x 3.5 | 6 x 3 | 4 x 4 |
| | 0.50 | 5.2 | 4.5 x 4.5 | 6 x 4 | 6 x 4 | 6 x 4 | 8 x 4 | 5 x 5 | 6 x 6 x 6 | | 0.75 | 5.8 | 5 x 5 | 6.5 x 4.5 |
| 7 x 5 | 9 x 4.5 | 6 x 6 |
| | 1.00 | 6.5 | 5.5 x 5.5 | 7 x 5 | 7 x 5 | 8 x 5 | 10 x 5 | 6.5 x 6.5 |
| | 1.25 | 7.0 | 6 x 6 |
| 7.5 x 5.5 |
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| | 1.50 | 7.4 | 6.25 x 6.25 | 8.5 x 5.5 | 8 x 6 | 9 x 6 | 11 x 5.5 | 7 x 7 |
| | 1.75 | 7.8 | 6.5 x 6.5 |
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| | 2.00 | 8.2 | 6.75 x 6.75 | 9 x 6.5 | 8.5 x 6.5 | 10 x 7 | 12 x 6 | 8 x 8 | 7 x 7 x 7 | | 2.25 | 8.6 |
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| | 2.50 | 8.8 |
| 9 x 7 | 9 x 7 | 12 x 7 | 13 x 6.5 | 8.5 x 8.5 | 9 x 9 x 9 | | 2.75 | 9.1 |
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| | 3.00 | 9.4 | 8 x 8 | 10 x 8 | 10 x 8 | 12 x 8 | 14 x 7 | 9 x 9 | 10 x 10 x 10 | | 3.25 | 9.7 |
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| | 3.50 | 10.0 |
| 10 x 8.5 | 10x 8.5 | 13 x 8 | 14 x 7.5 | 9.5 x 9.5 |
| | 3.75 | 10.2 |
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| | 4.00 | 10.4 |
| 11 x 9 | 11 x 9 | 14 x 8 | 16 x 8 | 10 x 10 |
| | 4.25 | 10.6 |
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| | 4.50 | 10.8 |
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| 11 x 9.5 | 14.5 x 9 |
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| | 4.75 | 11.0 |
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| | 5.00 | 11.2 |
| 12 x 10 | 12 x 10 | 15 x 9 | 16 x 8.5 | 11 x 11 |
| | 5.25 | 11.4 |
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| | 5.50 | 11.6 |
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| | 5.75 | 11.75 |
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| | 6.00 | 11.9 |
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| | 6.25 | 12.1 |
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| | 7.00 | 12.5 |
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| | 7.50 | 12.85 |
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| | 7.75 | 13.0 |
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| | 8.00 | 13.1 |
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| | 8.25 | 13.27 |
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| | 8.50 | 13.4 |
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| | 8.75 | 13.5 |
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| | 9.00 | 13.65 |
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| | 9.75 | 14.0 |
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| | 10.25 | 14.4 |
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| | 12.00 | 15.0 |
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| | 13.00 | 15.45 |
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| | 14.50 | 16.0 |
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