Diamond Carat Weight

Carat weight is the easiest to understand of the Cs. A diamond's weight is measured in carats. The carat is subdivided into 100 equal parts called 'points.' One point equals .01 carat or 1/100 carat. A half‐carat diamond is 50 points. A one carat diamond equals 100 points.


Carat weight may be expressed in both fractions and in decimal numbers. Diamond weight fractions are approximate and refer to ranges of weight.

Fraction Carat Weight Fraction Carat Weight
1/10 ct. 0.085‐0.11 1-1/4 ct. 1.23‐1.28
1/8 ct. 0.115‐0.14 1-1/3 ct. 1.29‐1.36
1/6 ct. 0.145‐0.17 1-1/2 ct. 1.45‐1.57
1/5 ct. 0.18‐0.22 1-5/8 ct. 1.58‐1.68
1/4 ct. 0.23‐0.28 1-3/4 ct. 1.69‐1.79
1/3 ct. 0.29‐0.36 1-7/8 ct. 1.80‐1.94
3/8 ct. 0.37‐0.44 2 ct. 1.95‐2.11
1/2 ct. 0.45‐0.57 2-1/4 ct. 2.23‐2.28
5/8 ct. 0.58‐0.68 2-1/3 ct. 2.29‐2.36
3/4 ct. 0.69‐0.79 2-1/2 ct. 2.45‐2.57
7/8 ct. 0.80‐0.94 2-3/4 ct. 2.69‐2.79
1 ct. 0.95‐1.11 3 ct. 2.95‐3.11

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0.5 ct.

1.0 ct.

2.0 ct.

3.0 ct.

5.0 ct.

Courtesy of GIA

It's important to note that a diamond's carat weight does not equal size. Because of differences in depth and cut, two diamonds with identical diameters may in fact be two completely different sizes. Therefore, it is possible to buy a diamond that looks bigger than another that may actually have a smaller carat weight. When buying a diamond, consider the length, width and depth of a stone as well as the surface of the diamond (the part that will actually show when the diamond is set).