Carats

Diamond sizes are usually quoted in carats. Although this is basically a simple measure it often causes confusion, possibly because a similar word is used completely differently when referring to gold!

What is a Carat?

The carat value of a diamond refers to its weight. That's all.

The word "carat" originally derived from the word for a "carob bean", which was used as the standard against which diamonds were weighed. A modern metric carat is defined as being one fifth of a gram (200 milligrams). A carat can be subdivided into 100 points. A diamond with more carats is heavier than one with less.

On reason this confuses people is that it's not easy to judge the weight just by looking at a diamond. Doubling the weight does not necessarily mean doubling the apparent size. A huge amount depends on the cut of the stone.

Nor is there a simple relationship between the carat rating of a stone and its price. Even ignoring other factors (eg Clarity, Colour, Cut), doubling the weight of a diamond is likely to more than double its price. Larger diamonds are rarer and hence more expensive than smaller ones.

The "other factors" mentioned above are important to remember. Diamonds are normally rated according to the "4 Cs": Carat, Clarity, Colour, Cut. Although bigger is generally better, a well cut 1 carat diamond might look much more impressive than a badly cut 2 carat stone.

Gold

Much confusion arises from the fact that the word "carat" - or "karat" - is also used to refer to gold. In the case of gold, the word refers to purity not weight. The carat weight of diamonds does not directly measure purity.

In the US the spelling karat is usually used when referring to gold, however in many other countries both words are spelt the same.