BUYING A DIAMOND: CARAT WEIGHT
The carat weight comes from ancient times when the unit of measurement for the diamond was a carob seed. The weight of the seed from the carob tree was judged to be equal to 1.00 carat.
Today, diamond weight is actually a metric measurement, with one carat being equal to 0.2 grams. Diamond weight is measured with electronic balances or, for diamonds already mounted, calculated by measuring the diamond's dimensions using a screw micrometer.
Diamonds are sold per carat. If you are buying a .50 ct diamond that is $3,800 per carat, you'll be spending $1,900 for the diamond. The larger the diamond, the more expensive per carat it will be.
Jewelers often talk about a half carat but may not mean exactly 50 points or .50 ct. In the diamond business, a half carat diamond can be within the .50 to .59 range.
Remember that carat is not the same as karat. Carat refers to gemstone weight while karat refers to the fineness of gold.
