Education - Loose Diamonds

When it comes to selecting or valuing stones, people often refer to the 4 Cs of diamonds. These are ‘carat’, ‘cut’, ‘color’ and ‘clarity’. But what do each of these actually mean and what should you look for when shopping for unset diamonds? Here, we look at each of those Cs in turn to help you understand how to choose a diamond.



Carat is a measure of the weight of a diamond. The term derives from the ancient method of weighing precious metals against the seeds of the carob tree which were considered to be even in weight. At the Fourth General Conference of Weights and Measurements in 1907, it was agreed that one diamond carat would equal 200mg of diamond. Diamonds are usually measured in points with 100 points equalling one carat or 200 mg. A one carat diamond will be expressed as 1.0ct and a half carat displayed as 0.5ct.

Carat weight is a key factor in determining the value of a diamond, but it is not necessarily the fact that the heavier a diamond is the greater its value. Two diamonds of equal carat weight may vary in value based on the other 3 Cs.