Round Brilliant Diamond Size Chart

Actual mm dimensions for round brilliant diamonds at every carat weight.

Round

How big is act Round Brilliant?

Round Brilliant Sizes

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MM Size	Carat Weight
0.8 mm	0.002 ct
0.9 mm	0.004 ct
1 mm	0.005 ct
1.1 mm	0.0068 ct
1.2 mm	0.0085 ct
1.3 mm	0.01 ct
1.4 mm	0.012 ct
1.5 mm	0.015 ct
1.6 mm	0.018 ct
1.7 mm	0.019 ct
1.8 mm	0.025 ct
1.9 mm	0.028 ct
2 mm	0.03 ct
2.1 mm	0.035 ct
2.2 mm	0.04 ct
2.3 mm	0.045 ct
2.4 mm	0.055 ct
2.5 mm	0.06 ct
2.6 mm	0.065 ct
2.7 mm	0.075 ct
2.8 mm	0.085 ct
2.9 mm	0.093 ct
3 mm	0.1 ct
3.1 mm	0.11 ct
3.2 mm	0.13 ct
3.3 mm	0.14 ct
3.4 mm	0.15 ct
3.5 mm	0.17 ct
3.6 mm	0.19 ct
3.7 mm	0.2 ct
3.8 mm	0.22 ct
3.9 mm	0.23 ct

MM Size	Carat Weight
4 mm	0.25 ct
4.1 mm	0.26 ct
4.2 mm	0.28 ct
4.3 mm	0.3 ct
4.4 mm	0.33 ct
4.5 mm	0.36 ct
4.6 mm	0.4 ct
4.7 mm	0.43 ct
4.8 mm	0.45 ct
4.9 mm	0.48 ct
5 mm	0.5 ct
5.1 mm	0.53 ct
5.2 mm	0.56 ct
5.3 mm	0.58 ct
5.4 mm	0.63 ct
5.5 mm	0.66 ct
5.6 mm	0.7 ct
5.8 mm	0.75 ct
6 mm	0.84 ct
6.3 mm	0.93 ct
6.5 mm	1 ct
6.8 mm	1.25 ct
7 mm	1.3 ct
7.3 mm	1.5 ct
7.8 mm	1.75 ct
8 mm	2 ct
8.7 mm	2.5 ct
9.1 mm	3 ct
9.8 mm	3.5 ct
10.3 mm	4 ct
11 mm	5 ct

Approximate dimensions for well-cut stones. Always verify against the grading report.

About round brilliant diamond measurements

These are approximate face-up dimensions for well-cut round brilliant diamonds with standard proportions. Actual size depends on cut depth, girdle thickness, and length-to-width ratio choices.

Always check the specific mm measurements on the grading report before buying. A stone that's technically 1 carat but cut deep will look noticeably smaller than one cut to proper proportions.