The word ‘carat’ is a unit of measurement which is used to indicate the weight of diamonds and gem stones. The word ‘carat’ has been used since 1913 against the metric system, in which case a carat equals around 0.2 grams or 0.007 ounces. The weight in carat is measured up to three decimal points and then rounded off to the closest hundredth.
However, the word ‘carat’ when it comes to diamonds is often confused with the overall visual size, even though it’s in fact just measurement of weight. This will vary depending on the size and the type of diamond being weighed, in which case its visual appearance will differ. For instance a 1.00 ct. round cut diamond that measures 6.5mm, and then a 1.00 ct. round cut sapphire will approximately 6.0mm which is 0.5mm less, being that the sapphire is heavier than the diamond.
The word ‘Carat’
Before the twentieth century the majority of jewellers measured diamonds using carob seeds, these were smaller, more uniform and so served the purpose of offering a good, consistent counterweight. So this is where the word “carat” originates from i.e. the word ‘Carob’.