When it comes to 'Carats' it's important to know your onions.

A 'Carat' is the unit of measurement denoting a gemstones weight. In total there are five carats to a gram. This weight system dates from the Middle Ages and the 'Troyes System of Mass', originating from the town of Troyes, once a prolific French trading town in gold, silver and precious and semi-precious gemstones.

. If you are slightly puzzled by the difference between a 'Carat' and 'Karat' then here's some clarification. A 'Karat' is a measurement of gold purity not weight. A 'Carat' is a system of weight not purity.

. Sometimes you will hear the word 'Point' when jewelers talk, especially when he or she is talking about diamonds. A 'Point' is a sub-division of a 'Carat'. There are 100 'Points' to a 1 'Carat' gemstone, consequently there are 50 'Points' to a half 'Carat', 25 'Points' to a quarter 'Carat' and so on.

. Again, with diamonds a very small gemstone of 0.02 to 0.20 Carats, used in a pave or channel setting, is referred to as 'Melee'.