Diamond Carat Weight is the metric measurement of how much a diamond weighs. One Carat is equal to 200 milligrams, or 0.2 grams.
With everything being equal, the price of a diamond will increase as the diamond’s carat weight increases, because larger diamonds are more rare and in greater demand. However, two diamonds of equal carat weight can have very different prices if the other three Diamond Cs (Color, Clarity, Cut) are not of the same quality.
It is important to keep in mind that a diamond’s true value is determined by the combined value of the quality of all of the diamond’s 4Cs.