Diamond Size Chart

Diamond size is the most visual of the 4 C’s of diamonds. Diamonds can be measured in both carat weight and millimeter. The millimeter tells you the true size of the diamond. With our diamond carat charts you can understand the millimeter differences between round and fancy shaped diamonds. While diamonds are looked at in terms of carat weight and purchased based on carat weight, it is important to consider millimeter measurements. Carat is the standard unit of measurement for diamonds and when compared to the metric system, one carat is equivalent to 0.2 grams. This is because a diamond of the same carat weight can have slightly different faceting and therefore look larger than it's carat weight equivalent. If looking for a diamond that looks larger faceup, consider getting a fancy shape diamond. Oftentimes, shapes like emerald, oval and pear look larger than their round counterparts. It is important to consider carat weight, millimeter measurements and ratios when looking at any diamond to optimize for the best possible option within your budget.

Additionally, if purchasing a diamond for an existing ring setting, be sure to look at the millimeter measurements of the diamond ring. Depending on the style of the setting, you may need to select a diamond that has very exact and precise millimeter measurements. Millimeter measurements are also important to consider when purchasing non-round diamond shapes like cushion and emerald. This is because the millimeter measurements will indicate if the cushion diamond is squarish and if the emerald diamonds have more rectangular measurements. This enables you to choose a shape that is the most visually appealing to you. Use our diamond sizing charts to understand the corresponding carat weights for well cut diamonds. When shopping for diamonds, the carat weight and the millimeter measurements can always be found on the GIA certificate of the diamond. One final diamond trade and wholesaler term that you may hear is pointers. This is also equivalent to certain millimeter sizes and carat weights. For example, a one-pointer is equivalent to a 0.01 carat diamond and so forth. These terms are typically used when describing smaller accent diamonds on diamond engagement rings or jewelry. Feel free to use these terms when talking with a jeweler and as you are researching. While each diamond is unique, be sure to educate yourself on average millimeter sizes of different diamond carat weights in order to find the best possible option for yourself.

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Round Diamond Size Chart

Round brilliant diamonds are among the most versatile and aesthetically pleasing shape for diamonds in the world. At its most ideally proportionate cut and finish, the 57-faceted round brilliant cut diamond can literally outshine most other diamonds on the market. As the first of the diamond shapes, the round brilliant cut is the most popular diamond shape for jewelry, especially engagement rings.The size of a round diamond affects the stone’s color saturation, as well as its clarity and light performance. Although a .25 carat round brilliant diamond may be as ideally proportioned and well-polished as a 1 carat gem, the smaller diamond is more compact and has a smaller table surface.


MM SizeCarat Weight
0.8 mm. 0.0025 ct.
1 mm. 0.005 ct.
1.15 mm. 0.0067 ct.
1.12 mm. 0.0075 ct.
1.25 mm. 0.01 ct.
1.3 mm. 0.01 ct.
1.5 mm. 0.015 ct.
1.75 mm. 0.02 ct.
1.8 mm. 0.025 ct.
2 mm. 0.03 ct.
2.25 mm. 0.04 ct.
2.5 mm. 0.06 ct.
2.75 mm. 0.08 ct.
3 mm. 0.11 ct.
3.25 mm. 0.14 ct.
3.5 mm. 0.17 ct.
3.75 mm. 0.21 ct.
4 mm. 0.25 ct.
4.25 mm. 0.28 ct.
4.5 mm. 0.36 ct.
4.75 mm. 0.44 ct.
5.0 mm. 0.50 ct.
5.25 mm. 0.56 ct.
5.5 mm. 0.66 ct.
5.75 mm. 0.75 ct.
6 mm. 0.84 ct.
6.25 mm. 0.93 ct.
6.5 mm. 1.00 ct.
6.8 mm. 1.25 ct.
MM SizeCarat Weight
7 mm. 1.30 ct.
7.3 mm. 1.50 ct.
7.5 mm. 1.67 ct.
7.75 mm. 1.75 ct.
8 mm. 2.00 ct.
8.25 mm. 2.11 ct.
8.5 mm. 2.43 ct.
8.7 mm. 2.50 ct.
9 mm. 2.75 ct.
9.1 mm. 3.00 ct.
9.5 mm. 3.35 ct.
9.75 mm. 3.61 ct.
10 mm. 3.87 ct.
10.25 mm. 4.16 ct.
10.5 mm. 4.41 ct.
10.75 mm. 4.57 ct.
11 mm. 4.91 ct.
11.25 mm. 5.49 ct.
11.5 mm. 5.85 ct.
12 mm. 6.84 ct.
12.25 mm. 7.26 ct.
12.5 mm. 7.36 ct.
12.75 mm. 7.52 ct.
13 mm. 8.51 ct.
13.5 mm. 9.53 ct.
14 mm. 10.49 ct.
15 mm. 12.89 ct.
16 mm. 16.06 ct.
17 mm. 18.00 ct.
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Princess Diamond Size Chart

Princess cut diamonds are currently the biggest competition to the round brilliant cut throughout the nation. The perfectly square shape provides a beautiful, “sharp” alternative to the round cut diamonds. The price of princess cut diamonds is also considerably less than the round ones, because more of the rough diamond gets used, rather than wasted, and the prices reflect the jeweler’s profit savings.

The princess cut diamond’s most noticeably altered characteristic based on its size chart measurements is its light performance. A princess cut diamond in any size has an immaculate sparkle (due in part to the retention rate of the original rough diamond), but the shine of each facet becomes more brilliant the larger the diamond is.



MM SizeCarat Weight
1.5 mm. 0.015 ct.
1.75 mm. 0.03 ct.
2.00 mm. 0.06 ct.
2.25 mm. 0.08 ct.
2.50 mm. 0.10 ct.
2.75 mm. 0.13 ct.
3.00 mm. 0.18 ct.
3.25 mm. 0.26 ct.
3.50 mm. 0.29 ct.
3.75 mm. 0.31 ct.
4.00 mm. 0.39 ct.
4.25 mm. 0.44 ct.
4.50 mm. 0.50 ct.
4.75 mm. 0.64 ct.
5.00 mm. 0.75 ct.
5.25 mm. 0.75 ct.
5.50 mm. 1.00 ct.
5.75 mm. 1.11 ct.
6.00 mm. 1.25 ct.
6.25 mm. 1.39 ct.
6.5 mm. 1.50 ct.
6.75 mm. 1.75 ct.
7 mm. 2.00 ct.
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Cushion Diamond Size Chart

The cushion cut diamond is a compromise between the round cut diamonds and shapes that have sharp corners and edges (princess, rectangle, etc.). As a more “vintage” diamond cut, cushion cut diamonds have often been overlooked and underrated in favor of more modern, “fancy” shaped diamonds. However, today they are in the top five most popular diamond cuts, and make an especially prominent appearance in jewelry worn by royalty and celebrities.

With the modernization of the cushion cut, the culets that detracted from the original cushion cut diamond’s beauty have reduced to unnoticeable ratios, and the facet appearance has grown smaller and more delicate. With increasing size, cushion cut diamonds show more of the faceting and clarity.


MM SizeCarat Weight
4.2 mm. 0.40 ct.
4.9 mm. 0.50 ct.
5.25 mm. 0.75 ct.
5.5 mm. 1.00 ct.
6 mm. 1.25 ct.
6.5 mm. 1.50 ct.
7 mm. 2.00 ct.
7.5 mm. 2.50 ct.
8 mm. 3.00 ct.
8.5 mm. 3.50 ct.
9 mm. 4.12 ct.
9.5 mm. 5.09 ct.
10 mm. 5.62 ct.
11 mm. 7.44 ct.
12 mm. 9.52 ct.
13 mm. 12.66 ct.
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Emerald Diamond Size Chart

Emerald cut diamonds resemble rectangle shaped gems, except that, like the cushion cut, the corners are softer and more rounded. These are one of the more popular diamond cuts for vintage style jewelry, and for paring with real and synthetic emeralds. Because of the elongated shape of emerald cut diamonds, they sometimes lose some of their shine. However, because of the same trait, even a .25 carat emerald cut diamond could easily appear almost twice as big.


MM SizeCarat Weight
3x2 mm. 0.10 ct.
3.5x2 mm. 0.12 ct.
4x2 mm. 0.15 ct.
4x3 mm. 0.20 ct.
5x3 mm. 0.29 ct.
5.5x3.5 mm. 0.46 ct.
6x4 mm. 0.50 ct.
6.5x4.5 mm. 0.75 ct.
6.5x4.5 mm. 0.88 ct.
7x5 mm. 1.00 ct.
7.3x5.3 mm. 1.25 ct.
7.5x5.5 mm. 1.50 ct.
8x6 mm. 1.75 ct.
8.5x6.5 mm. 2.00 ct.
MM SizeCarat Weight
9x7 mm. 2.50 ct.
10x7.5 mm. 3.00 ct.
9.5x7.5 mm. 3.21 ct.
10x8 mm. 3.79 ct.
11x9 mm. 5.21 ct.
12x8 mm. 5.34 ct.
12x10 mm. 6.00 ct.
14x8 mm. 6.25 ct.
13x9 mm. 6.38 ct.
14x10 mm. 8.48 ct.
13x11 mm. 9.13 ct.
14x12 mm. 11.26 ct.
16x12 mm. 14.22 ct.
17x13 mm. 16.50 ct.
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Oval Diamond Size Chart

The oval cut is a popular choice for women who want unique, non-mainstream styles of jewelry. As with the emerald cut diamonds, oval cut diamonds have an elongated shape, which has a slimming effect on the hands and fingers of the wearer.When an oval cut diamond is cut to ideal depth proportions, it has a similar brilliance to the round cut diamonds that brightens and appears lighter as the carat size increases.


MM SizeCarat Weight
4.5x3.5 mm. 0.21 ct.
5x3 mm. 0.21 ct.
5.5x3.5 mm. 0.33 ct.
5x4 mm. 0.35 ct.
6x4 mm. 0.50 ct.
6x5 mm. 0.61 ct.
6.5x4.5 mm. 0.65 ct.
7x5 mm. 0.75 ct.
7.7x5.7 mm. 1.00 ct.
8x6 mm. 1.25 ct.
9x6 mm. 1.41 ct.
8.5x6.5 mm. 1.50 ct.
9x7 mm. 2.00 ct.
MM SizeCarat Weight
10x8 mm. 2.50 ct.
10.5x8.5 mm. 2.88 ct.
12x8 mm. 3.00 ct.
11x9 mm. 3.85 ct.
12x10 mm. 5.05 ct.
14x10 mm. 5.81 ct.
13x11 mm. 6.05 ct.
14x12 mm. 8.21 ct.
15x12 mm. 8.76 ct.
16x12 mm. 9.32 ct.
16x14 mm. 11.88 ct.
18x13 mm. 12.86 ct.
20x15 mm. 14.96 ct.
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Pear Diamond Size Chart

Pear cut, or tear drop shaped diamonds, are comparable to the oval cut diamonds on the uniqueness scale. Although this cut can be used to create one-of-a-kind, anti-traditional engagement rings, these diamonds are more commonly used in earrings or solitaire necklaces.

Color is a prominent characteristic of pear cut diamonds, especially in the rounded bottom part of the stone. The tip loses some of its color in smaller sized carats, but the bottom and body of the diamond do not!


MM SizeCarat Weight
3x2 mm. 0.13 ct.
4x2.5 mm. 0.18 ct.
4x3 mm. 0.21 ct.
5x3 mm. 0.25 ct.
5x4 mm. 0.35 ct.
6x4 mm. 0.50 ct.
6.5x4.5 mm. 0.60 ct.
7x5 mm. 0.75 ct.
7.5x5.5 mm. 0.85 ct.
7.7x5.7 mm. 1.00 ct.
8x6 mm. 1.25 ct.
8.5x6.5 mm. 1.50 ct.
10x6 mm. 1.71 ct.
8.7x6.7 mm. 1.80 ct.
9x7 mm. 2.00 ct.
10x8 mm. 2.50 ct.
11x7.50 mm. 2.61 ct.
13x8 mm. 2.98 ct.
11x8 mm. 3.00 ct.
MM SizeCarat Weight
12x8 mm. 3.00 ct.
12x7 mm. 3.12 ct.
12x9 mm. 3.44 ct.
14x8 mm. 3.47 ct.
13x9 mm. 4.11 ct.
14x9 mm. 4.25 ct.
15x9 mm. 5.06 ct.
14x10 mm. 5.41 ct.
13x11 mm. 5.65 ct.
15x10 mm. 5.75 ct.
16x9 mm. 5.86 ct.
16x10 mm. 6.27 ct.
17x10 mm. 6.46 ct.
15x11 mm. 7.36 ct.
18x11 mm. 8.14 ct.
16x12 mm. 8.99 ct.
18x12 mm. 9.35 ct.
18x13 mm. 10.21 ct.
19x14 mm. 11.70 ct.
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Marquise Diamond Size Chart

Also known as football shaped diamonds, the marquise cut is another popular stone shape in vintage and antique style jewelry. It is also among the diamond styles that look larger compared to other cuts and shapes. Facet number is one characteristic that can change dramatically, depending on size. Since each diamond is cut a little differently based on its intended size, anywhere from 50-60 facets is not uncommon for marquise cut diamonds.

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MM SizeCarat Weight
3x1.5 mm. 0.025 ct.
3.5x1.75 mm. 0.065 ct.
3.5x2 mm. 0.07 ct.
4x2 mm. 0.10 ct.
3.75x1.75 mm. 0.11 ct.
4.25x2.25 mm. 0.12 ct.
5x2.5 mm. 0.14 ct.
5.5x2.75 mm. 0.16 ct.
5.5x3 mm. 0.18 ct.
5x3 mm. 0.20 ct.
6.5x3 mm. 0.23 ct.
6x3 mm. 0.25 ct.
7x3 mm. 0.30 ct.
7.5x3.5 mm. 0.33 ct.
7x4 mm. 0.34 ct.
8x4 mm. 0.50 ct.
8.75x4.25 mm. 0.70 ct.
9x4.5 mm. 0.75 ct.
MM SizeCarat Weight
9.5x2 mm. 0.85 ct.
10x5 mm. 1.00 ct.
11x5.5 mm. 1.25 ct.
11.5x6 mm. 1.33 ct.
12x6 mm. 1.50 ct.
13x6.5 mm. 2.00 ct.
14x7 mm. 2.50 ct.
15x7 mm. 3.00 ct.
14x8 mm. 3.00 ct.
15x7.5 mm. 3.25 ct.
15x8 mm. 3.44 ct.
16x8 mm. 3.86 ct.
16.5x8.25 mm. 4.00 ct.
17x8.5 mm. 4.88 ct.
17.5x10 mm. 5.50 ct.
20x8 mm. 7.08 ct.
20x10 mm. 7.94 ct.
20x11 mm. 9.50 ct.
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Asscher Diamond Size Chart

In the center of all properly cut and finished asscher cut diamonds sits a windmill design. This pattern forms as a result of the step-cut, similar to that of the emerald cut diamonds. The step cut style the asscher cut diamond shares with emerald cut diamonds does not diminish in smaller carat asscher diamonds. The biggest difference between sizes is that the patterns become more compact.


MM SizeCarat Weight
4 mm. 0.39 ct.
4.5 mm. 0.50 ct.
5 mm. 0.75 ct.
5.5 mm. 1.00 ct.
6 mm. 1.25 ct.
6.5 mm. 1.50 ct.
7 mm. 2.00 ct.
7.5 mm. 2.50 ct.
MM SizeCarat Weight
8 mm. 3.00 ct.
8.5 mm. 3.50 ct.
9 mm. 4.12 ct.
9.5 mm. 5.09 ct.
10 mm. 5.62 ct.
11 mm. 7.44 ct.
12 mm. 9.52 ct.
13 mm. 12.66 ct.
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Radiant Diamond Size Chart

This cut is a combined adaptation of the emerald, round and asscher cut diamonds. The unique but elegant combination goes by many names (usually an emerald or rectangle modified cut), and it makes for one of the most modern style stones on the market. No single characteristic varies from one carat size of radiant cut diamond to another. The entire unique stone just becomes a more compact version of larger ones, adding to its uniqueness.


MM SizeCarat Weight
5x3 mm. 0.31 ct.
4.5x3.5 mm. 0.34 ct.
6x3 mm. 0.41 ct.
6x4 mm. 0.50 ct.
6.5x4.5 mm. 0.75 ct.
7x5 mm. 1.00 ct.
7.3x5.5 mm. 1.25 ct.
7.5x5.8 mm. 1.50 ct.
8x6 mm. 2.00 ct.
8.5x6.5 mm. 2.25 ct.
9x7 mm. 2.50 ct.
9.5x7.5 mm. 3.00 ct.
10x7 mm. 3.31 ct.
MM SizeCarat Weight
10x8 mm. 3.50 ct.
11x9 mm. 5.05 ct.
12x9 mm. 6.06 ct.
11.5x10 mm. 6.45 ct.
13x9 mm. 6.54 ct.
12x10 mm. 6.79 ct.
14x10 mm. 8.47 ct.
13x11 mm. 9.33 ct.
13.5x11.5 mm. 10.19 ct.
15x11 mm. 11.48 ct.
14x12 mm. 12.14 ct.
16x12 mm. 14.22 ct.
17x13 mm. 16.22 ct.
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Selecting a Diamond Size

As the size of the diamond increases, the price also does up at an increasing rate. This is because larger diamonds are increasingly rare to find. When shopping for a diamond, consider the carat weight and understand the that millimeter size can vary for diamonds of the same carat weight. While diamonds are cut precisely using machinery, there can be slight variations that are affected by inclusions or other natural factors in the diamond. Diamonds can also have varying depths that affect the millimeter sizes when looking at the diamond face-up.

If concerned about diamond sizing, always remember that you can ask a gemologist about the ideal proportions of that shape. The gemologist will quickly be able to tell you if the diamond falls within the ideal proportions for that carat range. Oftentimes, diamonds that are priced lower than expected are in that price range because the millimeter sizing of the diamond is less than ideal. Always be sure to weight diamond size with other factors like clarity and color as there is no point comporomising significantly just to get a larger diamond. Be sure to weight all diamond features before you make your diamond purchase.



Gemologist Buying Tips

  • Critical or Magic Weights: Buying a diamond below certain cara weight cut offs will provide larger savings. Consider diamonds at 1.40ct vs. 1.50 carat, for example. The visual difference is very small, but the saving are large.

  • Choose diamonds that are cut very well. Those diamonds tend to have less depth and more spread. This means their measurements are larger making the diamond look visually larger than its carat weight. Cut is the most important element to focus on when selecting a diamond. It can make all the difference.

  • Carat tends to be the most visual and popular of the 4 C's. Therefore you should hone in on the carat weight first. Remember though, carat weight isn't the only thing that matters - it must be balanced with considering all the other factors like carat, color and clarity.
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