Diamond Carat Weight
The weight of a diamond is calculated in units called carats. One carat is one fifth of a gram (200mg) and is divisible into 100 ‘points’ where each point is equal to 0.01 carat.
It is important not to confuse carat weight with a diamond’s size. Whilst they are related, several other factors determine how large the diamond looks. They include the millimetre width across the top of the stone and its cut. For example, a shallow stone will look bigger from the top whereas a deeper stone of the same carat weight will look smaller. Diamond shape can also be a key factor. Elongated shapes such as marquise cuts and ovals can maximise the carat weight, making them appear visibly larger than rounded stones with an identical carat weight.
The measurement across the top of the stone is significant since this is how the diamond will be viewed when set in a piece of jewellery. The cut grade is important as this will give you the optimum fire and sparkle. A well cut diamond returns the maximum light out of the top of the stone and thus makes the diamond appear larger. A single diamond with a weight of one carat has significantly more value than a cluster of diamonds with a total weight of one carat.
Diamonds more often than not are cut to a rounded carat weight (for example 0.50ct, 0.70ct, 1.00ct) to achieve a higher price. Diamonds that fall short of the barrier, i.e. 0.49ct, 0.69ct, are called ‘undersized’ diamonds and will often look no different in size but will be less costly. Diamonds that are cut slightly over the boundaries are known as oversized diamonds and also offer great value for money.
When deciding what carat weight is right for you it is important to remember that it’s all about proportion: the smaller the finger the bigger the diamond will look. If you are looking for the largest carat weight to suit your budget then consider a diamond with a lower colour and clarity. Setting styles also can make your diamond look bigger. Consider a rub-over setting or a semi rub-over setting to create this illusion.