Diamond Carat Weight

Discover more about carat weight - the special unit of measurement used to weigh diamonds and gemstones.

What Is Carat Weight?

The special unit of measurement used to weigh diamonds and gemstones is called ‘carat’. Sometimes confused with the visual size of stones, it refers to weight only. The size does impact different stones’ measurements though. Shapes and types of gemstones can show slightly different readings due to variable densities. For instance, a 1.00 carat round sapphire might measure 6.0 mm, yet a 1.00 carat round diamond will measure 6.5mm. T.C.W. stands for ‘Total Carat Weight’, describing the weight of all gemstones or diamonds in a jewellery item - when there are more than one - in total. Earrings featuring diamond solitaires, for instance, are commonly cited in T.C.W. – the combined weight of both stones being indicated.

How Does Carat Weight Affect Price?

The carat weight of a diamond can be tailored to various budgets according to its cut, colour and clarity. Because they are harder to find, bigger diamonds are generally more valuable than smaller stones. Prices rise exponentially with diamond carats. For instance, a diamond which is 1.00 carat of a certain quality will always be more valuable than two diamonds of the same quality which are each half the size, or 0.50 carats each. As a rule of thumb, usually with diamonds, double the weight means four times the price. Diamonds which are just below a cut-off weight are known as ‘under-sizes’. There are not very many, and they can represent excellent value. The attractiveness of a diamond may sometimes be compromised so that it makes the cut-off weight, however this is not common. Cut-off weights are 0.50ct, 0.75ct, 1.00ct, 1.50ct and 2.00ct, which are known as the ‘magic numbers’ in the diamond industry.

Diamond Carat Size Chart

This diamond size chart is the perfect way to visualise the different appearance of diamonds when they vary in carat weights. It is worth noting that as 'carat' refers to weight, diamond shapes will appear different due to their differing measurements.

view diamond size chart

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