The 4 C's When selecting a diamond, it is important to have an understanding of the 4 C's. But what are the 4 C's and what in the world do they actually mean? Here is a brief explanation of cut, carat weight, color, clarity, and what they mean when you are picking a diamond. Cut Carat Color Clarity   A diamond's weight is the simplest of the 4 Cs to measure. A carat is equal to 0.2 grams. Each carat is divided into 100 points. A quarter carat has 25 points or written as 0.25 carats. Carat weight has no bearing on a diamond's cut, color, or clarity.