Gemstone Cuts, Carats (ct) & Sizing

Diamond Cuts

Diamonds used in jewellery come in a range of shapes, sometimes called ‘cuts’. Our jewellery designers use many of them in their beautiful creations. The most popular diamond shapes are described below.

Diamond Carat (ct)

The word “carat” comes from the carob tree, whose seeds were used as a standard for weighing precious gems in ancient times. 

Carat weight is important because it influences the size of the diamond, but the distribution of weight can vary between diamonds with the same carat weight. 
Diamond Size

Diamond dimensions are different for every diamond shape. Dimensions are a good indicator of how well a diamond has been cut for it to reflect the maximum amount of light.

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Brilliant Cut
Classic diamond shape
0.06-0.08cts = 2.5mm
0.10-0.12cts = 3mm
0.16-0.18cts = 3.5mm
0.20-0.22cts = 3.8mm
0.24-0.26cts = 4mm
0.27-0.29cts = 4.2mm
0.30-0.35cts = 4.5mm
0.36-0.38cts = 4.6mm
0.39-0.43cts = 4.7-4.8mm
0.44-0.47cts = 4.8-4.9mm
 0.48-0.52cts = 5mm
 0.53-0.59ctsct = 5.2mm
 0.60-0.62cts = 5.3-5.4mm
 0.63-0.68ctsct = 5.5-5.6mm
 0.69-0.74cts = 5.6-5.8mm
 0.75-0.80cts = 5.9-6mm
 0.90-0.92cts = 6.2-6.3mm
 0.93cts-0.99cts = 6.3-6.4mm
1.0cts-1.05cts = 6.4-6.5mm
Approx 1.1cts = 6.6mm
Approx 1.25cts = 6.8-6.9mm
Approx 1.3cts = 7mm
Approx 1.4cts = 7.2-7.3mm
Approx 1.5cts = 7.5mm
Approx 1.75cts = 7.7-7.8mm
Approx 2cts = 8-8.2mm

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Princess Cut
Elegant and modern
0.06-0.08cts = 2.1-2.2mm
0.10-0.12cts = 2.5-2.7mm
0.16-0.18cts = 3mm
0.20-0.22cts = 3.2-3.3mm
0.24-0.26cts = 3.4-3.5mm
0.27-0.29cts = 3.5mm
0.30-0.35cts = 3.8-3.9mm
0.36-0.38cts = 3.8-3.9mm
0.39-0.43cts = 3.9-4.1mm
0.44-0.47cts = 4.1-4.3mm
0.48-0.52cts = 4.3-4.5mm
0.53-0.59ctsct = 4.6mm
0.60-0.62cts = 4.7mm
0.63-0.68ctsct = 4.8mm
0.69-0.74cts = 4.8-4.9mm
0.75-0.80cts = 4.9-5mm
0.90-0.92cts = 5.1-5.2mm
 0.93cts-0.99cts = 5.2-5.3mm
1.0cts-1.05cts = 5.3-5.5mm
Approx 1.1cts = 5.8mm
Approx 1.25cts = 6mm
Approx 1.3cts = 6.1mm
Approx 1.4cts = 6.2mm
Approx 1.5cts = 6.4mm
Approx 1.75cts = 6.6-6.8mm
Approx 2cts = 7mm

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Emerald Cut
Excellent cut and clarity
0.25ct = 4X3mm
0.35ct = 5X3mm
0.40ct = 5X3.5mm
0.50ct = 5X4mm
0.60ct = 6X3mm
0.70ct = 6X4mm
0.80ct = 6.5X4.5mm
0.95ct = 7X4mm
1.00ct = 7X5mm
1.25ct = 7.5X5.5mm
1.50ct = 8X5mm
2.00ct = 8.5X6.5mm
2.25ct = 9X6mm
2.50ct = 9X7mm

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Marquise Cut
Distinctive curved shape
0.07ct = 4X2mm
0.15ct = 5X2mm
0.20ct = 5X3mm
0.25ct = 6X3mm
0.35ct = 6.5X3.5mm
0.35ct = 7X3mm
0.40ct = 6.5X4mm
0.50ct = 7X4.5mm
0.70ct = 8X5mm
0.70ct = 9X4mm
0.75ct = 9X4.5mm
0.80ct = 9X5mm
1.00ct = 9X6mm

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Oval Cut
Beautiful and radiant
0.15-0.18ct = 4X3mm
0.25ct = 5X3mm
0.40ct = 5X4mm
0.50ct = 6X4.5mm
0.65ct = 6.5X4.5mm
0.75ct = 7X5mm
1.00ct = 7.5X5.5mm
1.25ct = 8X6mm
1.50ct = 8.5X6.5mm
1.75ct = 9X6mm
2.00ct = 9X6mm

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Pear Cut
Unique and sophisticated
0.15-0.18ct = 4.5X3mm
0.25ct = 5X3.5mm
0.35ct = 5.75X4mm
0.40ct = 6X4mm
0.50ct = 6.5X4.5mm
0.75ct = 7X5mm
1.00ct = 8X5mm
1.50ct = 9X6mm