The weight or size of a diamond is measured in carats (ct.).
One carat weighs 1/5 of a gram and is divided into 100 points, so a diamond weighing 1.07 ct. is referred to as "one carat and seven points."
For example :
• 0,75 carat = 75 points
• 1/2 carat = 50 points
• 1/4 carat = 25 points
With an accuracy of 1/100,000 carat, the IGI scales provide a highly precise diamond weight, down to the hundredth or thousandth of a carat.
It is important to note that diamonds of the same weight don't necessarily have the same size appearance. Those cut too shallow or deep may look small for their weight, or suffer in brilliance. As a reference, IGI recommends the following vertical spreads for round brilliant diamonds.
Diamond prices rise exponentially with carat weight. So, a 2-carat diamond of a given quality is always worth more than two 1-carat diamonds of the same quality.