Diamond is the most hardest precious gemstone. Round cut diamond has many reflecting facets and it is also called as 'brilliant cut'. It resembles the shape of the cone and provides the maximum brightness at the top. Mass of the diamond is measured using carat weight. Diamond size chart / Diamond carat to mm weight chart provides the decimal width and weight for the round cut diamond from 1.0mm to 10.0 mm. 57 facets round cut diamond carat size is the most popular shape in the world.
| Round Cut Diamond Weight Chart | |||||
|---|---|---|---|---|---|
| mm Width |
Decimal width | Weight | mm Width |
Decimal width | Weight |
| 1.0 mm | .039 inch | .005 carat | 4.8 mm | .40 carat | |
| 1.2 mm | .008 carat | 4.9 mm | .43 carat | ||
| 1.3 mm | .01 carat | 5.0 mm | .197 inch | .47 carat | |
| 1.5 mm | .015 carat | 5.2 mm | .205 inch | 1/2 carat | |
| 1.7 mm | .02 carat | 5.4 mm | .60 carat | ||
| 1.8 mm | .025 carat | 5.5 mm | .63 carat | ||
| 2.0 mm | .079 inch | .03 carat | 5.6 mm | .65 carat | |
| 2.1 mm | .035 carat | 5.8 mm | .228 inch | 3/4 carat | |
| 2.2 mm | .04 carat | 6.0 mm | .236 inch | .80 carat | |
| 2.4 mm | .05 carat | 6.2 mm | .85 carat | ||
| 2.5 mm | .06 carat | 6.4 mm | .95 carat | ||
| 2.7 mm | .07 carat | 6.5 mm | .255
inch or 1/4 inch |
1.00 carat | |
| 2.8 mm | .08 carat | 6.6 mm | 1.10 carat | ||
| 2.9 mm | .09 carat | 6.8 mm | 1.17 carat | ||
| 3.0 mm | .118 inch | 1/10 carat | 7.0 mm | .276 inch | 1-1/4 carat |
| 3.1 mm | .11 carat | 7.2 mm | 1.33 carat | ||
| 3.2 mm | .125
inch or 1/8 inch |
.12 carat | 7.4 mm | .291 inch | 1-1/2 carat |
| 3.3 mm | .14 carat | 7.6 mm | 1.60 carat | ||
| 3.4 mm | .15 carat | 7.8 mm | .307 inch | 1.75 carat | |
| 3.5 mm | .16 carat | 8.0 mm | .315 inch | 1.90 carat | |
| 3.6 mm | .17 carat | 8.2 mm | 323 inch | 2.00 carat | |
| 3.7 mm | .18 carat | 8.4 mm | 2.15 carat | ||
| 3.8 mm | .150 inch | 1/5 carat | 8.6 mm | .338 inch | 2.25 carat |
| 3.9 mm | .22 carat | 8.8 mm | .346 inch | 2.50 carat | |
| 4.0 mm | .158 inch | .23 carat | 9.0 mm | .354 inch | 2.65 carat |
| 4.1 mm | .162 inch | 1/4 carat | 9.2 mm | 2.85 carat | |
| 4.2 mm | .30 carat | 9.4 mm | .370 inch | 3.00 carat | |
| 4.4 mm | .173 inch | .33 carat | 9.6 mm | 3.15 carat | |
| 4.5 mm | .35 carat | 9.8 mm | 3.35 carat | ||
| 4.6 mm | .181 inch | 1/3 carat | 10.0 mm | .394 inch | 3-1/2 carat |
Even though the carat weight is 50% for 1 carat stone, the diamond carat size of 0.5 is approximately equal to 5.2mm. This diamond carat to mm weight conversion is applicable for all weights, based on the length to width ratio of 1:1.
