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.