Round Brilliant Cut Diamond Size Chart + Weight Calculator

Wondering how big a 1-carat Round Brilliant Diamond is or how much a 6mm Round Brilliant Diamond weighs?

Then you have come to the right page as I have created a full chart and built a really easy-to-use calculator to help you get an idea of how much your Diamond weighs.

Quick Note: These are estimated weights only, the actual weight of your Diamond may be different depending on the proportions of the stone.

Round Brilliant Cut Diamond Weight Calculator

Not all Round Brilliant Cut Diamonds are perfectly round, which is why I created a calculator the help you estimate the weight of your Diamond.

Simply enter the length and width of the stone, the form estimates the depth based on these measurements but you can enter your own figures if you have them.

Round Brilliant Cut Size to Carat Chart

A D Color Diamond Table Up

1/4 Carat = 4.1mm

A D Color Diamond Table Up

1/2 Carat = 5.1mm

A D Color Diamond Table Up

1 Carat = 6.5mm

A D Color Diamond Table Up

2 Carat = 8.1mm

A D Color Diamond Table Up

3 Carat = 9.3mm

Images are for illustration purposes only as it is very difficult to accurately represent image sizes on screens.

SizeWeight
1mm0.004ct
1.1mm0.005ct
1.2mm0.006ct
1.3mm0.008ct
1.4mm0.010ct
1.5mm0.013ct
1.6mm0.015ct
1.7mm0.018ct
1.8mm0.022ct
1.9mm0.026ct
SizeWeight
2mm0.030ct
2.1mm0.034ct
2.2mm0.040ct
2.3mm0.045ct
2.4mm0.051ct
2.5mm0.058ct
2.6mm0.065ct
2.7mm0.073ct
2.8mm0.082ct
2.9mm0.091ct
SizeWeight
3mm0.10ct
3.1mm0.11ct
3.2mm0.12ct
3.3mm0.13ct
3.4mm0.14ct
3.5mm0.16ct
3.6mm0.17ct
3.7mm0.18ct
3.8mm0.20ct
3.9mm0.22ct
SizeWeight
4mm0.23ct
4.1mm0.25ct
4.2mm0.27ct
4.3mm0.29ct
4.4mm0.31ct
4.5mm0.33ct
4.6mm0.36ct
4.7mm0.38ct
4.8mm0.41ct
4.9mm0.43ct
SizeWeight
5mm0.46ct
5.1mm*0.49ct
5.2mm0.52ct
5.3mm0.55ct
5.4mm0.58ct
5.5mm0.61ct
5.6mm0.65ct
5.7mm0.68ct
5.8mm0.72ct
5.9mm0.76ct
5.15mm is equal to 0.50 or 1/2 carat
SizeWeight
6mm0.80ct
6.1mm0.84ct
6.2mm0.88ct
6.3mm0.93ct
6.4mm0.97ct
6.5mm1.00ct
6.6mm1.07ct
6.7mm1.11ct
6.8mm1.17ct
6.9mm1.22ct
SizeWeight
7mm1.27ct
7.1mm1.33ct
7.2mm1.38ct
7.3mm1.44ct
7.4mm1.50ct
7.5mm1.57ct
7.6mm1.63ct
7.7mm1.69ct
7.8mm1.76ct
7.9mm1.83ct
SizeWeight
8mm1.90ct
8.1mm*1.97ct
8.2mm2.05ct
8.3mm2.12ct
8.4mm2.20ct
8.5mm2.28ct
8.6mm2.36ct
8.7mm2.45ct
8.8mm2.53ct
8.9mm2.62ct
Just over 8.1mm equals 2 carats
SizeWeight
9mm2.71ct
9.1mm2.80ct
9.2mm2.89ct
9.3mm*2.99ct
9.4mm3.09ct
9.5mm3.19ct
9.6mm3.29ct
9.7mm3.39ct
9.8mm3.50ct
9.9mm3.61ct
Just over 9.3mm equals 3 carats
SizeWeight
10mm3.72ct
11mm4.95ct
12mm6.43ct
13mm8.17ct
14mm10.21ct
15mm12.55ct
16mm15.24ct
17mm18.28ct
18mm21.70ct
19mm25.52ct

I hope these charts are helpful but I do have to state that these should be used as guides only as the actual weight of your Diamond may be more or less than the weight listed above.

This is because every Diamond has its own unique proportions that impact the weight of the Diamond, with things like:

  • Girdle thickness
  • Crown angle
  • Pavilion angle

All having an impact on the weight of the Diamond and this does make weight estimation a challenge and why it is not always best to just use size charts.

The calculator is more accurate for weight estimation as you can enter exact measurements but this is still only an estimated weight and the actual weight of your Diamond might be different.

If you want to do this for other shapes, then check out my Diamond weight estimation calculator or take a look at my size charts for other styles of cut below:

Other Diamond Size Charts

I'm Paul Haywood FGA DGA, the owner and founder of Haywoods Gems, I'm a fully qualified Gemmologist and Diamond Grader from the Gemmological Association of Great Britain.

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