Carat is the traditional unit of measurement we use to describe the weight of a diamond or coloured gemstone. It is the equivalent of 0.2g and allows us to be accurate in accounting for very tiny differences in weight since one carat is itself divided into 100 ‘points’. A stone of half a carat may also be described as 0.50ct or 50 points.

The weight of a diamond is of course closely related to its size, but it also has a relationship to the stone’s cut. Two diamonds may have the same carat weight but look different in size if one is cut a little deeper than the other. As discussed in our previous post about diamond cuts, it is not always an advantage to simply choose the largest stone; it is important to look at all the details of a diamond before making a purchase. A shallower stone might look a little larger, but it may also appear dull and lifeless as it does not interact with light in the most effective way.

You may notice that a piece containing a cluster of diamonds with a total weight of 1.00ct costs considerably less than a piece set with a single diamond of the same weight.  Both the rings pictured above have a carat weight of 1.00ct; the cluster with seven stones combining to produce that weight, the solitaire with a single one carat diamond.  The quality of the diamonds and the cost of the mounts is very similar for the two pieces, but the price of the solitaire is more than double that of the cluster.  This is because the price of a diamond increases with size, so the combined price of seven approximately 0.14ct stones is less than the price of one 1.00ct stone.

Certain carat weights are particularly popular: it is desirable to own a stone of half a carat or one carat. If a diamond reaches these sought after weights the price can increase more dramatically as there is more demand for them.

An awareness of the effect carat weight has on price can help you to make an informed decision about what diamond to buy. We often choose round brilliant cut diamonds weighing around 0.46ct, just under the half carat mark, as these have the approximate diameter of a half carat stone without the price increase that comes once that size has been reached. They can therefore offer the same visual appearance for a reduced price.  In the rings above both diamonds measure approximately 5mm in diameter but the one on the left weighs 0.46ct and the one on the right weighs 0.50ct  The stones are the same quality, but choosing the slightly lighter stone can save you more than 20%.  A similar choice is available when looking at other sizes such as 0.90ct and 1.00ct stones.

Our showroom is staffed with experienced and highly qualified jewellers, and our team will be happy to help you when choosing a diamond.  We can advise you on how to get the most out of your budget and find the perfect stone to suit your requirements.  You can also browse a selection of our diamond jewellery on our website.