Diamond Metric, English, Carat conversion chart

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Diamond Metric, English, Carat conversions.
Welcome to our millimeters to carat conversion chart for round brilliant cut diamonds. This chart depicts weight for round cut diamonds. Use this chart as a guide noting that these figures are calculated for optimum cut diamonds and that actual weight can vary per quality of cut.

Find Metric/English conversions in our "Metric Inch Conversion Chart" to the right. There is also a, very clear, short briefing on why physical size not carat weight is preferred in mounting gemstones or diamonds in jewelry at "About Calibrated Gems" that you should acquaint your self with.

We have highlighted some of the pertinent sizes for you to check and get a good idea of the actual size of a diamond. These charts are for diamonds and do not correlate to other types of gemstones.

For more diamond information, visit our "Four C's diamond grading chart" to the right.
 

Diamonds				Diamonds
Round Cut	Decimal Inch			Round Cut	Decimal Inch
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