Diamond Carat

Visualize different carats of diamonds on a hand, a bust, an ear

Compare carat size

How to choose the carat weight of your diamond?

  diamond weight choice

Diamond, a mass of light, is not represented. Any figuration of this precise stone is below, next to, reality. A loss. The figuration of the weight of the diamond? What the eye sees is not the weight, it is a volume, a brilliance. A diamond appears much larger than its diameter, by the play of brilliance of these facets.

of diamonds
by carat

0.30 carat





VAT Diamond Price

780 €

0.50 carat






VAT Diamond Price

1522 €

0.70 carat






VAT Diamond Price

2649 €

1 carat






VAT Diamond Price

5305 €

What is the size of a diamond according to its carat weight?

  Carat diamond weight

The diameter? The carat, unit of measurement, measures weight and not diameter. A 1 carat diamond is not twice as large as a 0.50 carat diamond, only 25-30% larger (see table on the right), but costs more than double that. To help you better visualize the size of a diamond, we indicate in the table below the approximate diameter of a diamond (round brilliant shape) according to its carat weight.

In the Jewelry section of our site, on each of the jewelry cards (of solitaire, rings, pendants and earrings), you will also find a carat comparator that will allow you to visualize the visual effect of a diamond set and worn (on a hand, a bust, an ear), according to its carat weight and its diameter.

Please also note that the precise dimensions of the diamond are always indicated on the GIA, HRD or IGI quality certificate. You can see the online copy of the certificate by clicking on "see certificate" of each diamond card from our certified diamonds catalog.


Timeless collection

How much does a diamond cost according to its carat weight?


A diamond, whether big or small, does not weigh much, but it is the factor that "weighs" the most on the price. This is why in our diamond catalog, we start with the weight and a price range, and then refine the other criteria.

There is no single answer to the often asked question: "what is the price per carat of a diamond? Two diamonds of the same weight often have very different values: it all depends on their certificate, quality of cut, shape, color and purity.

The question is then to know which diamond quality criteria you prefer according to your budget.


How much does a 1 carat diamond weigh?


The weight of a diamond is measured in carats. A 1 carat stone is equivalent to 0.20 grams. Diamond is such a specific material that it has its own unit of weight: the carat. This is conventionally set at 200 milligrams, or one fifth of a gram. The word comes from the Greek "keration", which is the seed of the carob tree: of fairly uniform weight, it was used as a unit of measurement in the Greek spice markets. These seeds of about 200 milligrams were considered as good units of weight measurement for weighing gems (diamond, sapphire, ruby, emeralds...) before the invention of fairly sensitive scales.


For more information, please do not hesitate to contact us at info@i-diamants.com or +33 (0)4 22 45 08 70.


The term has a different acceptance. In the appreciation of gold, the carat refers to the purity of the alloy: 24 carats correspond to 99% pure gold. The carat of gold is therefore the proportion of this precious metal in the jewel, pure gold being 24 carats and most jewelry to 18 carats, or three quarters of gold, or more exactly: 750 thousandths of pure gold and 250 thousandths of various alloys. 14 carat gold is made up of 585 thousandths of gold and 415 thousandths of various alloys. Recently, in response to the rise in the price of gold, the 9 carat title has appeared on the French market with the authorized appellation "gold". This gold contains only 375 thousandths of gold, i.e. 37.5% gold and 62.5% miscellaneous alloys. At i-diamants, we only offer 18 carat (750/000) gold jewelry. Other precious metals are also weighed in carats. For example, require that the platinum has a titre of 950/000, i.e. 950 thousandths of pure platinum and 50 thousandths of various alloys.

Find all our
diamond advice guides


What diamond criteria to favour ?


Diamond Certificates (GIA, IGI, HRD)


Diamond Clarity


Diamond Colour


Diamond Cut


Different shapes of diamonds

How do you measure the carat weight of a diamond?


It is because the price of the material is high that the diamond is weighed accurately. The unit of weight in carat is a determining factor in the quality and value of a diamond. The value of a 1.00 carat stone is exceptionally greater than a 0.99 carat stone. Diamonds are weighed using electronic microbalances with a sensitivity of up to five decimal places. Verification of the weight of the stones throughout the diamond chain is also an important security measure.

How to calculate the carat of diamonds on a jewel already set?

  Diamond dimensions

Whether the diamonds set on your jewelry looks big or small, the simplest method (without having to loosen the gemstones in the jewelry) is to measure the diameter of each one. With the cross-reference chart above, you can determine the carat weight of the diamonds in your jewelry. Attention this rule works for white diamonds and colored diamonds (pink, yellow diamonds...), whatever the degree of purity and color, but does not apply to other gems, precious stones (Sapphire, Ruby, Emerald) or fine stones, whose density is different. For an exact measurement of the dimensions of gemstones, it is still best to go to a jewelry store and ask for the help of a professional jeweler, because even with a calliper, measurement errors are easy.

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