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.