Diamonds were first discovered in India around 500 B.C. The first unit of weight used for diamond was the carob seed; the weight of a seed from the seed pod of the carob or locust tree was equivalent to a 1.00 ct. diamond.
Note: Do not confuse carat with karat. Carat refers to stone weight while karat refers to fineness of gold.
Determining the Carat Weight
The weight of a diamond is measured in carats. This is the easiest factor to determine. One carat is divided into 100 "points", thus a diamond with 75 points weighs .75 carats. However, two diamonds of equal weight may have a very unequal value, depending on their cut, color and clarity. Quality is not determined by weight alone.
Diamonds, today, are weighed using the metric system and the resulting weights are still converted into the carat as the unit of Diamond weight Devices used for calculating weight are the screw micrometer, the Moh gauge and the leverage gauge to mention a few.