Diamond Carat (ct) is the unit of measure used to define how much a diamond weighs. A single carat's weight is exactly 200 milligrams, although, carats are more regularly divided into 100 'points' for example, a 1.25ct diamond could be described as weighing 125 points.
A diamond can often be referred to as a quarter-carat or half-carat, which would indicate a weight of 25 points and 50 points respectively.
Typically, a diamond with a high carat weight is more valuable because larger stones are more rare and more desirable, however, it is not uncommon for other factors such as the diamond cut, clarity or colour to have an effect on the overall cost of a diamond.
For an approximate size to weight reference on two popular styles of diamond, the round and princess cut, see below.
