The value of a diamond is not determined by its size but by its weight, which is measured in carats. The word ‘carat’ originally comes from keration, the ancient Greek word for carob seeds, which were used to weigh and compare many goods in the ancient world. The weight of smaller diamonds is not expressed in carats, but in ‘points’.
A carat is made up of 100 points, so a half-carat diamond is also known as a 50 point diamond. Although used most famously for diamond jewellery, carat is also used as a standard measure for other gemstones. However, some gemstones are denser than others so different gems of the same weight are not necessarily the same size.
Larger diamonds normally have a higher value as they are rare and therefore in more demand for diamond jewellery than smaller diamonds of the same quality. Of course, a diamond being large does not automatically qualify it as valuable, as the quality of the cut, clarity and colour all need to be taken into consideration.
A large stone with poor cut, clarity and colour will not be worth any more simply because of its size. However, a large stone with excellent cut, clarity and colour will be worth more than smaller diamonds of equally good quality. For example, diamond rings consisting of one large two carat diamond will nearly always be more expensive than diamond rings made up of several smaller diamonds which may total two carats between them.
