The more a diamond weighs, all things being equal, the more it will cost. Weight is different than size. A diamond can look bigger and weigh less, depending on how it’s proportioned.
Diamonds are weighed in terms of points and carats. Carat comes from the carob seed, (from a tree in the Mediterranean region) which was a method of measure in ancient times. There are 142 carats to the ounce!
Because of the density difference between gemstones, two stones can appear to be the same size, yet have different weights. For example: Emerald weighs less than diamond, so an emerald that actually weighs 1 carat will look bigger than a 1 carat diamond. On the other hand, ruby weighs more than a diamond, so a ruby that weighs 1 carat will look smaller than a 1 carat diamond. As discussed previously, this is the result in differences in specific gravity.
The more out of round, the lower the price per carat.
Diamonds are priced on a per carat basis; the price jumps disproportionately, however, especially in the larger sizes.
|Weight in Carats||Diameter in Millimeters Diameter in Inches||(approximate)|
|0.01 ct||1.3 mm||1/20”|
|0.05 ct||2.4 mm||1/10”|
|0.10 ct||3.0 mm||1/8”|