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diamond carat explained

On this page you will find :

  • Diamond carat size explained
  • Diamond carat weight vs the price of a diamond
  • Selecting your diamond carat weight
  • The carat weight chart 
  • A video by GIA explaining the diamond carat size


Diamond Carat size

The carat size is the unit of measurement used to indicate the weight of a diamond. Since 1913 carat weight has been measured compared to the metric system with one carat equaling 0.2 grams. Diamond carat size is measured up to three decimals and rounded to the nearest hundred.

Find our recommendations on diamond clarities further in this page.


Diamond carat weight and price of the diamond

There is no linear link between the weight of the diamond (carat) and its price. As most rough diamonds that are mined are either too small or have an inferior quality to produce diamonds that are used in the jewelry market it can take up to one million rough diamonds to produce one single one carat diamond. Due to the rarity of larger , high quality diamonds a one carat diamond can often by 4 to 6 times the price of a half carat diamond.


Selecting your diamond carat weight

Carat weight will be one of the most important factors that determine the price of your diamond. Below we listed some tips to consider when choosing which carat weight is right for you:

  • Diamond pricing is determined by carat weight and listed in half carat increments. Therefore a diamond with equal clarity and cut of one carat will cost more than a diamond weighing slightly less ( like 0.98 carat)
  • Carat indicates the weight of a diamond but the cut ( length and width specifically) determine the actual physical size. For selecting the most diamonds with more visual appearance ( larger surface) select rectangular shaped version of same carat weight like the oval or rectangular shaped sizes
  • Within the same shape two one carat diamonds could also have a different diameter. for example two one carat round diamonds could have a diameter of 6 or 6.5 mm wide. Broader diamonds create a greater visual impact. So the actual size of the diamond is not linked to its weight.
  • Prices of diamonds rise exponentially when carat weight increases. If your main selection factor is carat weight you could consider diamonds with a lesser clarity grade  or lesser colour grade to lower the overall price
  • If you buy a diamond to set in a ring, consider the ring size of the wearer. The smaller the hand or ring size, the lower carat weight you can select ( see our diamond size comparison chart )

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Carat Weight chart

The image is an example of the carat scale not representing actual size of the diamonds (depending on actual screen size)

Diamond carat

Diamond carat : a GIA education video


Further diamond education

Our diamond education pages help you to understand the 4 C's of diamond quality so yo can choose your next diamond wisely.

Learn more about :   the 4 C's of diamond quality - The different diamond shapes - Diamond certification



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