Diamond carat refers to the weight of a diamond. It is wrongly interpreted for the size.
The term carat derived from the Greek word keration meaning “fruit of the carob”. The carob was the tree used mainly by peoples of the Mediterranean and Middle East regions. The seeds are characterized for their remarkably equal weight, thus causing them to be practically identical. This trait allows for their weight to become a standard. Early jewelers used the carob the unit for measuring weight of the diamond. One carob seed equaled one carat.
Today, one carat is equivalent to 200 milligrams. One carat can also be divided into 100 “points”.
Therefore, a 0.25 carat diamond can be called a “25-point” or “1/4 carat” diamond.
It is more rare to find larger diamonds in nature. Therefore, a single 1.00 carat diamond will cost more than two 0.50 carat diamonds (assuming the color, clarity and cut are the same). Cut and mounting can make a diamond appear larger or smaller than its actual weight.