The standard measure for diamond weight is the "carat". A carat is 200 milligrams and is divided into 100 points ( for example, a 25 point diamond is 1/4 carat and would weigh 50 milligrams).
Carat weight is the easiest of the four C's to determine, however the diamond MUST be loose. Too many jewelers approximate carat weight, for instance, when you buy a 1/2 carat diamond, which you assume to be 50 points, you may actually be getting less than that. Many stores sell as low as 45 points, and present the stone as "approximately" a 1/2 carat.
Although the most obvious characteristic, carat weight is the least important in determining the brilliance and beauty of a diamond.
Continue to learn about the Color of Diamonds or if you're ready, take the GIA Diamond Buyer Primer Course.
