Carat weight is the physical weight of the diamond. A carat is a unit of weight measurement for diamonds and colored gemstones. One carat is divided into 100 points, with each point equaling 1/100th (.01) of a carat (ct.). So a diamond of 75 points weighs .75 carats. Carat weight is the easiest of the 4 C’s to determine. However, two diamonds of the same carat weight can have very unequal value, depending on their cut, clarity, and color.