The most obvious factor in determining a diamond's value is its size. However, two diamonds of the same size can have significantly different values because of the other C's explained in this guide. As with all precious gems, the weight or size of a diamond is measured in carats. For example, one carat is equal to 0.2 grams.
When weighing a diamond, 1.00 carat is divided into 100 points; therefore, a diamond described as 25 points is 0.25 carat or a quarter of a carat. The larger the diamond, the more rare and valuable it is, resulting in a higher price per-carat. For example, a two-carat diamond is more than twice as valuable as a one-carat diamond of the same quality and characteristics. Importantly, a diamond’s weight is different from a diamond’s size. A well cut diamond will look larger and brighter.