A diamond carat is a measurement of its weight, not its size, and is not to be confused with Karat, used for determining the purity of gold. The standard measurements for one carat is one fifth of a gram, or 200 milligrams. In clear diamonds, it is not unusual to see stones of five to ten carats.

However in colored diamonds, they tend to appear naturally in smaller sizes compared to other diamonds and gemstones. This is because ideal temperatures, pressure levels and chemical deposits are required in order for a diamond to achieve color, which is a natural anomaly and as a result very few are found in nature and the deposits are much smaller.

In fact, very few pink diamonds from the Argyle mine in Australia are over one carat in size. At last year’s Argyle tender, the largest pink diamond was 2.03 carats and most of the stones were between a third of a carat and one carat in size. Because colored diamonds have a higher price tag and are generally polished into smaller sizes, there is an active sub-carat collector market for these stones.