A carat equals 200 milligrams, or 0.007 ounces. Although the weight in carat is a measurable value, it is important to note that the size of a diamond does not increase linearly with the carat weight. In other words, a diamond of 2 carat is not twice as large as a diamond of 1 carat; It will seem slightly larger, but not twice as big.

The weight in carat is an important factor in determining the value of a diamond, but it must be balanced with other factors such as grinding quality, color and purity to assess the general beauty and sparkle of the stone. This means that a large carat weight may not be as valuable as a diamond of smaller carat size with excellent grinding quality and brightness.