The carat weight (actually mass) of a diamond measures the mass of a diamond. One carat is defined as exactly 200 milligrams (about 0.007 ounce). The point unit - equal to one one-hundredth of a carat (.01 carat, or 2 mg) - is commonly used to denominate the size of diamonds of less than one carat. All else being equal, the value of a diamond increases exponentially in relation to carat size. Larger diamonds are both rarer and more desirable for use as gemstones.
The price per carat does not increase smoothly with increasing size. Instead, there are sharp jumps around milestone carat weights, as demand is much higher for diamonds weighing just more than a milestone than for those weighing just less. As an example, a 0.95 carat diamond has a significantly lower price per carat than a comparable 1.05 carat diamond, due to differences in demand.
Total carat weight (t.c.w.) is a phrase used to describe the total mass of diamonds or other gemstone in a piece of jewelry, when more than one gemstone is used. Diamond earrings, for example, are usually quoted in t.c.w. when placed for sale, indicating the mass of both diamonds together and not each individual diamond.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Diamond".
