Carat measures a diamond's weight, not its size as often confused. Five carats are equal to one metric gram, or, one carat is equal to 200 milligrams. The heavier the diamond, the greater its value. Small stones of high color and clarity are easy to find than larger ones, so you will find them more common in jewelry stores.

Heavier stones, however, are harder to find, leading to greater value and use of supply and demand principles. Based strictly on weight, diamonds are incredibly valuable. The heavier the diamond, the rarer and the more valuable it is. Washington Diamond specializes in superior quality, GIA certified diamonds of all shapes, ranging from one-half carat and up for engagement rings.