Selini Bespoke Jewellery
About Diamonds - Carat Weight

Carat is often confused with size, but it is actually a measure of weight. The cut of a diamond can make it appear much larger or smaller than its actual weight.

High carat diamonds often appear to be brighter or more brilliant than lower carat equivalents due to the prism effect of light travelling over larger distances. However the carat weight is only one of the factors to take into consideration when appraising the quality of a diamond.

One carat is the equivalent of 200 milligrams. One carat can also be divided into 100 "points." A 0.50 carat diamond is the same as a 50 points or a 1/2 carat diamond.

Round brilliant cut diamond sizes

0.01ct (1 point) = 1.3mm
0.02ct (2 points) = 1.7mm
0.03ct (3 points) = 2.0mm
0.06ct (6 points) = 2.5mm
0.10ct (10 points) = 3.0mm

0.25ct (25 points) = 4.0mm
0.50ct (50 points) = 5.0mm
0.75ct (75 points) = 6.0mm
1.00ct (100 points) = 6.5mm

1.25ct = 7.0mm
1.50ct = 7.5mm
1.75ct = 7.8mm
2.00ct = 8.0mm
3.00ct = 9.0mm
4.00ct = 10.4mm
5.00ct = 11.2mm

It is often assumed that a 1.00 carat diamond costs exactly twice the price of a 0.50 carat diamond. This is not the case. Since larger diamonds are found less frequently, a 1.00 carat diamond will cost much more than twice that of a 0.50 carat diamond, assuming colour, clarity and cut remain the same.

It is worth noting that a 0.90ct diamond is only 0.25mm smaller in diameter than a 1.00ct diamond, this is because the bulk of the weight in a diamond is in the bottom part of the diamond. So although a 0.90ct will only look a little smaller from the top it will be significantly less expensive than a 1.00ct diamond. There is however a certain prestige attached to owning a 1.00ct diamond.

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