What is Carat Weight And Size of Gemstones?

How are Sapphires measured?

Precious gemstones vary in density, for example when comparing a diamond and a sapphire of the same size, the sapphire will be heavier due to it's larger density. Gemstones are often classified by carats, which is a unit of weight, but for ease of selection and setting, size is a more useful measurement for sapphires, which we list in millimeters (mm). Our standard size for a round sapphire is 6 mm, which is approximately one carat. Download the chart below and print it out for your own reference when selecting the size.

Sapphire and diamond actual size cut


These natural white sapphires demonstrate why the carat weight of a sapphire does not always equal the size in mm, these 3 Ceylon sapphires range from 2.54 ct to just over 3.75 cts even though each sapphire length and width are all almost identical.