The 4 C’s: Carat

An Expert Guide to Diamond Carat


Carat is the unit of measurement for the weight of diamonds, gemstones and pearls. A stone’s carat is determined by weighing the stone and calculating the carat from there. A Carat is the most precise metric for analyzing the value of a diamond.

To fully understand the carat of diamonds, we have broken down the key information for you including:

  • How to Calculate the Carat of a Diamond
  • How Carat Relates to Value
  • Approximate Sizes of a 2-Carat Diamond Based on Cut
  • How to Tell the What a Stone Will Look Like on a Hand
  • Some Tips and Tricks on How to Make the Most of a Diamond’s Carat
  • The History of a Carat


More Carats = More Value

A simple rule of thumb to remember is as diamond carat increases, so does the value of the stone. This is because larger stones that are high enough quality to be used in jewelry are rare. The rarer the stone, the higher the price tag it will demand.

One thing that is very important to keep in mind is that the value of the stone in relation to carat is not linear. Assuming that cut, color and clarity are equal, a 2-carat diamond will likely cost more than double the price of a 1-carat diamond. That is because 1-carat diamonds are more common.

It is often said that double the carat weight means four times the value. A 2-carat diamond should carry a price tag around 4-times the size of a 1-carat diamond, though this is not always the case.


Calculating a Carat

Gemologists use both the weight of the stone to calculate the carat:

1 Carat is equal to 0.200 (1/5 of a gram). This means that a diamond that is 3 carats would weigh 0.600 grams. All a jeweler needs to measure the carat of a stone is a balanced scale.

To get very specific on the weight of a stone, jewelers will measure diamonds down to two decimals. If a diamond is smaller than one carat, they will refer to this in points. For example, a .50-carat stone would be called a “fifty pointer.”

Why is it called a Carat?

No – it has nothing to do with the orange vegetable even though they are pronounced the same way. The word Carat actually has Arabic and Greek roots.

In the past, precious stones and metals were measured in relation to a ‘carob seed.’ It was widely believed that the carob seeds all weighed the same. This, however, was not accurate and led to a wide variety of definitions of a Carat around the world.

In 1907, at the Fourth General Conference on Weights and Measures, a universal measurement of 0.200 grams was adopted to equal 1 Carat.

How Can I Buy A Stone That Looks As Big As Possible?

There are a couple things you can do to make sure your stone looks as large as possible. Some optical illusions can help make your stones look larger. Keep these ideas in mind.


  • Band size can affect the look of the stone. For example, a thick band can make the center stone look smaller in comparison. However, if you were to opt for a thin band, it will make the center diamond look larger in proportion.
  • Fancy cut diamonds are often cheaper per carat than a round diamond. A fancy cut diamond is any diamond besides a round cut stone. They can come with lower price tags. Some cuts, like an emerald cut or a marquise cut look larger because of the proportions of the stone.
  • Opt for an off-sized stone. If you are looking for a 2-carat diamond but it is out of your price range, look at something in between 1.75 carats and 1.99 carats. These stones don’t have as high of a value because they don’t hit one of the “magic numbers” that jewelers aim to hit for stones. A stone that is 1.98 carats is imperceptible from a 2-carat ring, but it will come in at a price tag that is more comfortable.
  • A halo around the center stone will make it look bigger. Adding a halo of smaller stones around your center diamond will make the diamond look much bigger than it is.

How Big Will My Diamond Look?

The dimensions of a stone with the same carat will change based off the cut of the diamond. Below you can find the approximate sizes of a 2-carat diamond based off the cut:

Round Cut 2-Carat Diamond: 8.11 x 8.11 mm

Princess Cut 2-Carat Diamond: 7 x 7 mm

Cushion Cut 2-Carat Diamond: 8 x 7 mm

Asscher Cut 2-Carat Diamond: 7 x 7 mm

Oval Cut 2-Carat Diamond: 10.5 x 7 mm

Radiant Cust 2-Carat Diamond: 7.5 x 7 mm

Pear Cut 2-Carat Diamond: 10.5 x 7 mm

Emerald Cut 2-Carat Diamond: 8.5 x 6 mm

Heart Cut 2-Carat Diamond: 8.3 mm

Marquise Cut 2-Carat Diamond: 13 x 6.5mm

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Carat is the unit of measurement for the weight of diamonds, gemstones and pearls. A stone’s carat is determined by weighing the stone and calculating the carat from there.

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