« Help ! My man wants to buy me a diamond but I don’t know how to choose! » I have heard this too often! Keep cool! It’s not so complicated: follow a few basic rules and trust your eye and your heart, they are your best allies! The basic “4 C” rule makes it easy: The diamond has four evaluation criteria called the 4 C: Carat, Clarity, Colour, Cut. Let me explain : Carat: The weight of a diamond is expressed in carat and a carat is equal to 0.20 gram. The carat is divided into 100 points. For example a diamond of 0.50 carat is equal to a diamond of 50 points. Carat is also the unit of weight measurement of precious stones and fine stones.