Diamonds are measured in Carat Weight. One carat weighs 200 milligrams. If a diamond is referred to as four grains, this also means that it is a one carat diamond. The word Carat comes from the word carob. A carob is a bean that grows on a tree in the Mediterranean. In times past, if a diamond weighed the same as a carob bean, it was one carob, or one carat.

However, in the Far East, where Carob trees do not grow, rice was used to measure the weight of a diamond. If a diamond weighed as much as four grains of rice, it was four grains - or one carat as we know it to be now. The majority of diamond purchases are for diamonds that are 1/3 of a carat.

Beware when shopping for diamonds that are already set or mounted. If more than one diamond is used in the piece, the tag on the jewellery will give the CTW or Carat Total Weight - it does not tell you the carat weight of each stone in the piece. You need to ask the jeweller for the total carat weight of the largest diamond in the piece to truly understand what you are buying.

All about the Clarity of Diamonds

Clarity is an important aspect of a diamond, and it is important to know how to grade the clarity of a diamond before you buy one. It is actually quite easy to learn how to grade the clarity of a diamond. There are basically two things that you must understand: Diamonds with visual inclusions and blemishes, and those that are 'eye clean' meaning that there are no inclusions or blemishes that can be seen with the naked eye. From there, the clarity of a diamond is further broken down into subcategories.

Many people mistakenly think that diamond clarity refers to how clear it is. This isn't so. Clarity actually refers to the internal and external imperfections of the diamond. The best diamonds, of course get a grade of FL or IF - Flawless or Internally Flawless - meaning that it is perfect. A grade of I-1, I-2 or I-3 means that the diamond is imperfect, with a grade of I-3 being the worst.

Other grades are VVS1 and VVS2, which means that the diamond is very, very slightly imperfect; VS1 and VS2, meaning the diamond is very slightly imperfect; SI-1 and SI-2, which means that the diamond is slightly imperfect.