Carat Weight
The weight of a diamond is expressed in carats. This term comes from ancient times when gems were weighed against the carob bean. One carat is equal to 200 milligrams, or one fifth of a gram. One point equals 1/100th of a carat, so 25 points is equal to a quarter of carat and 50 points is equal to half of a carat.
Carat Weight and Cost:
As carat weight gets larger the value of the diamond increases disproportionately. This is because pieces of rough material are increasingly rare with size. Over a million pieces of rough must be mined to find one piece large enough to produce a 1 carat finished diamond. This means that a diamond twice as large as an identical, smaller one may be three or more times as expensive, depending on the market.
Carat Weight and CUT:
Carat weight is not the same thing as size. As diamonds increase in weight their apparent size becomes less predictable. Diamonds cut too shallow may appear larger than they should, while diamonds cut too deep may look smaller. Too shallow and too deep are both undesirable.
You should always use millimeter measurements and consider girdle thickness when judging proper spread for carat weight.
diameter guide for rounds
Superior cut can also result in edge-to-edge light performance. A well-cut diamond will appear larger than other diamonds of the same carat weight and spread).
