MM to CARAT Conversion

Buying a diamond online leads you to the challenge that you cannot touch the diamond before purchasing. The image will not show you the real size in comparison to your finger. So many people find it difficult to estimate the true size of the diamond without a comparison scale. Therefore I have created a scale per diamond shape, which translates the diamond size into carats. Underneath I have placed a ruler so that you can estimate exactly how big the diamond would be in your hand even from home.

Round Diamonds

Let´s start with the most important shape: the round diamonds. I guess that´s what most of you guys are looking for so you should check the size of the diamond before buying 2 carats just because of missing knowledge. Most of the people underestimate the size of lower carats. As you can see, even 0.5 carat diamonds are not that small as you might think. Just put your finger on it and you will see how big it is (but I know, depends on the finger).

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Princess Diamonds

The next one is the Princess diamond. This one usually is smaller than the round diamonds (compared within the same carat weights) but looks quite heavy due to it´s squares.

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Marquise Diamonds

For the Marquise diamonds you do not only have to watch the width, but especially the height. Marquise diamonds are narrow ones that look beautiful at a woman's  finger. As you can see the height goes up very fast with increasing carat weight. Hence better measure the finger before buying too much carats.

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Asscher Diamonds

Asscher diamonds are very similar to Princess diamonds, even the measurements.

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Heart Diamonds

Heart diamonds are real special shapes. In my opinion not everybody can wear these ones but that´s not the main topic here. The size of heart diamonds is quite similar to the round ones so if you have seen a round diamond before you can estimate how a heart diamond would look like.

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Pear Diamonds

Like Marquise diamonds the Pear diamonds are very high. The top is rounder and they are a little bit smaller but still similar. That’s why you have to check the finger´s size before buying a Pear diamond blindly.

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Emerald Diamonds

These are heavy ones. They are thick and wide so think wisely about your girlfriend and her style. Emeralds do not fit to everybody.

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Radiant Diamonds

Radiant diamonds are similar to Emeralds but a bit smaller. Have a look at the table and you will see the differences.

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Oval Diamonds

Again you see a diamond shape where you have to watch the height. Oval diamonds go high very fast so that you have to be careful with increasing carat weight.

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Cushion Diamonds

The Cushion diamond almost is squared and a little similar to the Radiant. It´s better to check the size here with a ruler because they can look really heavy.

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It is very important to consider the mm to carat conversion before buying diamonds. Each diamond shape has a different size, even if it is the same number of carats. So you can not only compare the carats and then transfer to the size of the diamond.

Let´s compare the Marquise diamond to Round diamonds: If you buy a jewel of 1 carat, there would be a considerable difference in size. The Marquise alone is 4 mm higher than the round one. This is a huge difference on the finger if your girlfriend is more of a petite person.

The best thing to do is to imagine roughly how big the diamond should look on her finger and then compare the mm to carat conversion per diamond shape to buy exactly the right size. I hope that my scales will help you to get an idea.

By the way: do you know where the unit carat comes from and what influence carat weight has on the price of the diamond?

If not, you can read my article on carat weight.