Defining Diamond Carat Weight

Let’s talk about the most objective of the Four Cs, carat weight.

Carat weight is the term used to describe the weight of diamonds and colored gemstones. In some countries Karat with a "K" is used, which might be a little confusing since Karat is used to describe gold pureness, 10K, 14K, 18K, etc.

The word carat evolved from the word "Carob" which is a type of seed. These seeds were so consistent in size and weight that they were used as counter weights when weighing diamonds in the early days of diamond trading.

How does a diamond grader determine the carat weight of a diamond?

Diamonds are priced per carat: 1 carat is divided into 100 points 1 carat = 1/5 of a gram. Which is about the weight of a paperclip.

Today highly accurate electronic scales are used and diamonds are weighed to 0.001, thousandth of a carat and rounded up. Diamonds are priced per carat so in large stones every last point counts!

Gem Scale

If all other Cs are equal, per carat price will be higher as carat weight increases. But do not assume that a two carat is twice as expensive as a one carat. Because two carat stones are far more rare, they will sell for a premium. Take a look at the examples below from James Allen.

1.01 Round G-Color, VS2, Cut Excellent $4860
2.01 Round G-Color, VS2 Cut Excellent $19,150
3.01 Round G-Color, VS2 Cut Excellent $44,540

Pro tip: When selecting a diamond stay just under the "Magic" weights. For instance, if cut, color and clarity are the same and you have the choice between a 0.48 stone and a 0.50 or 0.51, take the 0.48, as it will be less expensive and visually you will not see the slight difference in size.

This becomes more important as the size increases. Magic Numbers: 1.00, 1.50, 2.00, 2.50, etc.

What measurement do we use to describe diamonds smaller  than one carat and multiple small stones?

100 Points = 1.00 Carat

TW- Total weight: Collective weight of small accent stones or diamonds in pavé settings. E.G. 20 diamonds, 0.05 points each = 1.00 carat total weight.

The larger a diamond is, the more graders will examine the stone. Once the weight has been determined, and verified, it is noted on The Diamond Grading Report.

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GIA Reports (400 × 250 px).png
An independent nonprofit organization, GIA (Gemological Institute of America), established in 1931, is recognized as the world’s foremost authority in gemology. GIA invented the famous 4Cs of Color, Clarity, Cut and Carat Weight and, in 1953, created the International Diamond Grading System™ which is recognized around the world as the standard for diamond quality.

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Thank you for reading our article; please leave your comments and questions below.

Happy Shopping!

Francesca de Granville, G.G. (GIA) F.G.A.

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