The 4Cs

The 4Cs: Carat Weight

Carat weight has the most influence on diamond value. Diamonds of different shapes may appear different sizes for the same carat weight.

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

When diamonds are mined, large gems are discovered much less frequently than small ones, which makes large diamonds much more valuable. 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.

Diamond Carat Charts

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.

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