Diamond Carat Weight Chart in mm, Size and Conversion
Larger diamonds are rarer than smaller diamonds as large raw diamonds are less frequently found during mining while very small diamonds are relatively commonplace. As the carat weight of a diamond increases, so does its rarity and its value, thus prices will be exponentially higher as the carat weight rises.
A 1.00 carat diamond will be more than twice the price and value than that of a 0.50 carat diamond. The diamond weight will, broadly speaking, determine also the size of the stone, however a slightly deeper or more shallow cut may result in very slight variations in the size of the “face” of the diamond.
More inexpensive options to choose when looking to buy a diamond at a cheap price for the same size is to choose a carat weight that is considered an “under-size”. For example, a 0.99 ct diamond will sell at wholesale at a discount price compared to a full 1 ct diamond, making them more affordable at retail.
Needless to say, that in mountings (solitaire engagement rings, earrings, eternity wedding rings, bracelets), the difference cannot be detected. It is worth spending some time to search these affordable options online and see who is selling under-sizes. Please feel free to contact us about such diamonds as we regularly have them in our inventory.
Below is a chart displaying popular carat weights and their ideal average size in mm for round brilliant and princess cut diamonds:
Carat weight conversion to mm size chart: Round Brilliant Cut Diamond
| Carat weight | 1/2 ct | 3/4 ct | 7/8 ct | 1 ct | 1 1/4 ct | 1 1/2 ct | 1 3/4 ct | 2 ct | 3 ct |
| mm size | 5.1 mm | 5.9 mm | 6.1 mm | 6.5 mm | 7.0 mm | 7.4 mm | 7.9 mm | 8.1 mm | 9.3 mm |
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Carat weight conversion to mm size chart: Square Princess Cut Diamond
| Carat weight | 1/2 ct | 3/4 ct | 7/8 ct | 1 ct | 1 1/4 ct | 1 1/2 ct | 1 3/4 ct | 2 ct | 3 ct |
| mm size | 4.5 mm | 5.0 mm | 5.4 mm | 5.7 mm | 6.1 mm | 6.4 mm | 6.8 mm | 7.0 mm | 9.3 mm |
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• Carat weight is weight and not size. 1 carat (or ct) conversion is 1/20 gram
• Simulated diamonds will have not have the same weight conversion
