Diamond Carat

Diamond Carat is the most visual of the 4 C’s of diamonds. Carat is a weight measure for a diamond that is globally recognized. Not to be confused with karat (a measure of gold purity), a 1.00 carat or ct diamond weighs 0.20 grams. Contrary to popular belief, the carat is not the size of the diamond. The size of a diamond is measured in millimeters by length and width. It typically takes about 250 tons of rock mining to produce just 1.00ct of diamond. That is why diamonds are rare and expensive. Diamonds come in a variety of shapes and carat weights. A diamond cutter’s highest priority is to maximize carat weight of a diamond. The larger the diamond, the rarer and therefore more expensive it is. Diamonds are weighed with carat/gram scales very precisely to the 0.01ct.

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Diamond Scale: The Range

Diamonds within each carat range have average millimeter sizes so you can approximate their visual size. To truly understand the diamond’s size, evaluate the measurements. Well cut Round diamonds have less depth than well cut fancy shaped diamonds (diamonds other than Round). For example a 1.00ct Round diamond will have ~6.40mm length/width vs a 1.00ct Princess diamond, which will have ~5.50mm. Fancy shapes tend to have more weight and less size. Thus round cut diamonds have a premium versus fancy shapes of the same carat weight. Visually, it is very difficult to discern the difference between diamonds that vary 5% - 10% in carat weight. For example, 0.95ct vs. 1.00ct. One additional factor that affects diamond size is the cut of the diamond. If a diamond is cut too deep, it may looks smaller than a lower carat diamond. A deep 1.00ct diamond can possibly look visually smaller than a 0.95ct shallow cut diamond.


Diamond MM Chart

carat size chart with round diamonds showing the millimeter size of each popular diamond size

Carat Price Effect

Diamond pricing increases exponentially, not linearly, as diamond carat weight increases. Once a diamond hits it’s critical weight, the price bumps up. The critical weights are: 0.30ct, 0.40ct, 0.50ct, 0.70ct, 0.90ct 1.00ct, 1.50ct, 2.00ct, 3.00ct, 4.00ct, 5.00ct, 10.00ct. Diamond cutters will do everything they can to keep the diamond weight at or above each critical weight. Therefore, while it is often recommended to purchase 0.95ct diamonds vs. 1.00ct diamonds, it’s very difficult to find 0.95ct diamonds. Additionally, diamond manufacturers and suppliers know this “trick” and so they’ll price their diamonds accordingly.

The average diamond carat weight is 0.90ct. Consumers prefer Carat above the other C’s of diamonds because carat is the most visual C. When pricing diamonds, think about carat on one side and the other 3 C’s on the other side. In order to fit your diamond budget, as you increase carat, you may need to reduce the other C’s. Vice versa, if you increase the other C’s, you may need to decrease carat.

Please see our diamond price estimator to understand the approximate pricing across a variety of diamond sizes, when combined with the other diamond attributes.

0.25ct round diamond on a hand for diamond sizing 0.50ct round diamond on a hand for diamond sizing 0.75ct round diamond on a hand for diamond sizing 1.00ct round diamond on a hand for diamond sizing 2.00ct round diamond on a hand for diamond sizing 3.00ct round diamond on a hand for diamond sizing 4.00ct round diamond on a hand for diamond sizing 5.00ct round diamond on a hand for diamond sizing
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