The Gemological Institute of America (GIA) created the first, and now globally accepted standard for describing diamonds: Color, Clarity, Cut, and Carat Weight.
Today, the Four Cs of Diamond Quality is the universal method for assessing the quality of any diamond, anywhere in the world.
The creation of the Four Cs meant two very important things: diamond quality could be communicated in a universal language, and diamond customers could now know exactly what they were about to purchase.
In this article we take a comprehensive look at Carat Weight. If you prefer a more condensed version please check out our: “The Four Cs: An Overview” article.
A metric “carat” is defined as 200 milligrams. Each carat can be subdivided into 100 ‘points.’ This allows very precise measurements to the hundredth decimal place. The diamond carat weight of a diamond below one carat can also be described by its ‘points’ alone.
For instance, a diamond that weighs 0.25 carats could also be referred to as a ‘twenty-five pointer.’ Diamond weights greater than one carat are expressed in carats and decimals. A 1.08 carat stone would be described as ‘one point oh eight carats.’
You can buy coffee by the pound. You can even buy deli meat by the pound. Even if you’ve never bought a diamond, the correlation between weight and price is a concept that we can all understand. Therefore, the general perception is that a larger diamond is more valuable than a smaller one.
What is not as easy to understand is that a 2.00 carat diamond is not always worth twice as much as a 1.00 carat diamond. Large diamonds are rarer than smaller ones, so logically they seem to be worth more. But the value of a diamond is determined by considering all of the 4Cs of diamond quality as a whole.
Some weights are considered “magic sizes”–half carat, three-quarter carat, and carat. Visually, there’s little difference between a 0.99 carat diamond and one that weighs a full carat. But the price differences between the two can be significant.
To determine carat weight, the grader weighs the diamond using an extremely accurate electronic micro-balance that captures the weight to the precise fifth decimal place (the nearest ten-thousandth of a carat).
All else being equal, diamond price increases with diamond carat weight, because larger diamonds are more rare and more desirable. But two diamonds of equal carat weight can have very different values (and prices) depending on three other factors within the 4Cs: clarity, color, and cut.
We hope you found this article helpful in getting an overall sense of how Carat-weight affects value and subsequently the cost of a diamond. However, should you have any additional questions about this or any other jewellery related topics, you can always: “Ask Our Jeweller”
If you’re hungry for even more information on carat weight grading be sure to check out our video-post! (it was produced by The Gemological Institute of America)
You may also enjoy this “interactive application on The Four Cs.”
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