Diamond Size Chart

By: WC Editorial Team Read Time: 5 mins Diamond

May 26, 2023

Diamonds can be measured in both carat weight and millimeter. While diamonds are purchased based on carat weight — the standard unit of measurement for loose diamonds — it's important to consider millimeter measurements and ratios to choose the best possible option for your budget.

Why is a Diamond's Millimeter Measurement Important?

A diamond's millimeter measurement tells you its true size. That's because a diamond of the same carat weight can have slightly different faceting and therefore look larger than a carat weight equivalent. If you're looking for a diamond that looks larger faceup, consider getting a fancy shape diamond: Shapes like emerald, oval, and pear often look larger than their round counterparts.

Additionally, if you're purchasing a diamond for an existing ring setting, you'll want to look at the millimeter measurements. Depending on the style of the setting, you may need to select a diamond with a precise millimeter size.

Millimeter measurements are also important to consider when purchasing non-round diamond shapes like cushion and emerald. That's because the millimeter measurements will indicate if the cushion diamond is squarish; emerald diamonds will have more rectangular measurements.

(Just check out our diamond sizing charts below to see 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 certificate of the diamond. At With Clarity we give GIA certificates for all our natural diamonds and IGI certificates for all our lab grown diamonds.

What are "Pointers"?

A trade and wholesaler term you may hear is pointers, which is the equivalent to certain millimeter sizes and carat weights. A one-pointer refers to a 0.01 carat diamond. A two-pointer diamond refers to a 0.02 carat stone, and so forth. These terms are typically used when describing smaller accent diamonds on diamond engagement rings or jewelry. 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.

Round Diamond Size Chart

The most popular shape for engagement rings, the round brilliant diamond is versatile and aesthetically pleasing. At an ideal proportional cut and finish, the 57-faceted round brilliant cut diamond can literally outshine most other diamonds on the market. The size of a round diamond affects the stone’s color saturation, clarity and light performance.

MM Size	Carat 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 Size	Carat 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.

Princess Diamond Size Chart

Princess-cut diamonds are the biggest competition to the round brilliant cut. The perfectly square shape provides a beautiful, sharp alternative to round-cut diamonds, and a princess-cut diamond will cost also considerably less than a round cut. (That's because more of the rough diamond is used, not wasted, and the price reflects the jeweler’s savings.)

The princess cut diamond’s most variable characteristic based on size is light performance. In any size, a princess cut can have an immaculate sparkle (due in part to the retention of the original rough diamond), but the shine of each facet becomes more brilliant the larger the diamond is.

MM Size	Carat 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.

Cushion Diamond Size Chart

The cushion-cut diamond is a compromise between the round-cut diamond and shapes with sharp corners and edges (princess, rectangle, etc.). The cushion cut is a vintage style, but today it ranks among the five most popular diamond cuts. Cushion cuts are especially prominent 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 faceting and clarity.

MM Size	Carat 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.

Emerald Diamond Size Chart

Emerald-cut diamonds resemble rectangle-shaped gems, but like the cushion cut, their corners are softer and more rounded. They're one of the more popular diamond cuts for vintage-style jewelry and for pairing with real or synthetic emeralds. Because of the elongated shape of emerald-cut diamonds, they sometimes lose a bit of shine, but even a 0.25-carat emerald-cut diamond can easily appear almost twice as big.

MM Size	Carat 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 Size	Carat 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.

Oval Diamond Size Chart

The oval cut is a popular choice for women who prefer unique, non-mainstream jewelry. Like emerald-cut diamonds, oval-cut diamonds have an elongated shape and slimming effect on the hand. When an oval-cut diamond is cut to ideal depth proportions, it has a similar brilliance to round-cut diamonds. They brighten as carat size increases.

MM Size	Carat 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 Size	Carat 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.