Back to: Diamond Grading Basics
A “Carat” is the unit of measurement used when weighing a diamond. 1 carat is the equivalent of 0.2 grams.
The word originates from Ceratonia siliqua, commonly known as the Carob tree.
This allows very precise measurements to the hundredth decimal (100th) place. A jeweller may describe the weight of a diamond below one carat by its “points” alone. A diamond’s value is greatly determined by its weight. For example, if you had two identical diamonds i.e. same colour, clarity, and cut but the one weighs 1 carat and the other only half a carat, the 1-carat diamond may be worth as much as 350% more than the half carat.
1 Carat is divided into a 100 points.
- A point is a 100th of a carat
- 50 points = 0.50ct
- 25 points = 0.25ct
Diamonds are weighed to three decimal places and rounded off to a hundredth. The only time the weight is rounded off upwards is if the 3rd digit is a 9 (GIA)
For Example:
- 0.998 = 0.99ct
- 0.999 = 1.00ct
How to Weigh Rough & Polished Diamonds
Carat Weight Chart
Carat Comparison Chart
