Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use this diamond size chart to convert millimeters (mm) to carat weight for every popular shape. It works for both lab grown and mined diamonds, because they have the same density.

Quick Answers: Diamond Size in mm

  • 1 carat round diamond: about 6.5 mm across.
  • 2 carat round diamond: about 8.0 mm across.
  • How big is a 4 mm diamond? About 0.25 carat, a quarter carat.
  • Small melee stones: 1.3 mm is about 0.01 ct, 1.8 mm about 0.025 ct, 2 mm about 0.03 ct.

Moissanite Size to Carat

Moissanite is about 10% lighter than diamond, so it is sold by millimeter size and a diamond equivalent weight. A 6.5 mm round moissanite looks like a 1 carat diamond but actually weighs about 0.88 to 0.9 carat. Use the mm sizes in the chart below for both stones. Not sure which to choose? Read our moissanite vs lab grown diamond guide.

Select your shape below. Ready to shop? Browse lab diamond solitaire rings or moissanite solitaire rings, and check your fit with our ring size chart.

Select your diamond shape:
Round Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
4 mm 0.25 ct
5.0 mm 0.50 ct
5.75 mm 0.75 ct
6.5 mm 1.00 ct
6.8 mm 1.25 ct
7.3 mm 1.50 ct
7.75 mm 1.75 ct
8 mm 2.00 ct
8.7 mm 2.50 ct
9.1 mm 3.00 ct
9.75 mm 3.50 ct
10.25 mm 4.00 ct
10.75 mm 4.50 ct
11 mm 5.00 ct
MM Size Carat Weight
0.8 mm 0.0025 ct
1 mm 0.005 ct
1.1 mm 0.0067 ct
1.2 mm 0.009 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
2.2 mm 0.04 ct
2.5 mm 0.06 ct
2.75 mm 0.08 ct
3 mm 0.10 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 3.50 ct
10 mm 3.87 ct
10.25 mm 4.00 ct
10.5 mm 4.41 ct
10.75 mm 4.50 ct
11 mm 5.00 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
Princess Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
3.25 mm. 0.25 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.
6.75 mm. 1.75 ct.
7 mm. 2.00 ct.
7.5 mm. 2.50 ct.
8 mm. 3.00 ct.
8.5 mm. 3.50 ct.
8.75 mm. 4.00 ct.
9.25 mm. 4.50 ct.
9.5 mm. 5.00 ct.
MM Size Carat Weight
1.5 mm. 0.015 ct.
1.75 mm. 0.03 ct.
2 mm. 0.06 ct.
2.25 mm. 0.08 ct.
2.5 mm. 0.10 ct.
2.75 mm. 0.13 ct.
3 mm. 0.18 ct.
3.25 mm. 0.25 ct.
3.5 mm. 0.29 ct.
3.75 mm. 0.31 ct.
4 mm. 0.39 ct.
4.25 mm. 0.44 ct.
4.5 mm. 0.50 ct.
4.75 mm. 0.64 ct.
5 mm. 0.75 ct.
5.25 mm. 0.90 ct.
5.5 mm. 1.00 ct.
5.75 mm. 1.11 ct.
6 mm. 1.25 ct.
6.25 mm. 1.39 ct.
MM Size Carat Weight
6.5 mm. 1.50 ct.
6.75 mm. 1.75 ct.
7 mm. 2.00 ct.
7.25 mm. 2.01 ct.
7.5 mm. 2.50 ct.
7.75 mm. 2.74 ct.
8 mm. 3.00 ct.
8.25 mm. 3.24 ct.
8.5 mm. 3.50 ct.
8.75 mm. 4.00 ct.
9.25 mm. 4.50 ct.
9.5 mm. 5.00 ct.
9.75 mm. 5.36 ct.
10 mm. 5.62 ct.
10.25 mm. 5.76 ct.
10.5 mm. 5.99 ct.
11 mm. 7.44 ct.
11.5 mm. 9.44 ct.
12 mm. 9.52 ct.
Cushion Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
3.25 mm. 0.25 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.
6.75 mm. 1.75 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. 4.00 ct.
9.3 mm. 4.50 ct.
9.5 mm. 5.00 ct.
MM Size Carat Weight
3.25 mm. 0.25 ct.
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.
6.75 mm. 1.75 ct.
7 mm. 2.00 ct.
7.5 mm. 2.50 ct.
MM Size Carat Weight
8 mm. 3.00 ct.
8.5 mm. 3.50 ct.
9 mm. 4.00 ct.
9.3 mm. 4.50 ct.
9.5 mm. 5.00 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

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
4.30x3 mm. 0.25 ct.
6x4 mm. 0.50 ct.
6.5x4.5 mm. 0.75 ct.
7x5 mm. 1.00 ct.
7.5x5.3 mm. 1.25 ct.
7.5x5.5 mm. 1.50 ct.
8x6 mm. 1.75 ct.
8.5x6.5 mm. 2.00 ct.
9x7 mm. 2.50 ct.
9.3x7.5 mm. 3.00 ct.
9.75x7 mm. 3.50 ct.
10x8 mm. 4.00 ct.
10.5x8.5 mm. 4.50 ct.
11x9 mm. 5.00 ct.
MM Size Carat Weight
3x2 mm. 0.10 ct.
3.5x2 mm. 0.12 ct.
4x2 mm. 0.15 ct.
4x3 mm. 0.18 ct.
4.30x3 mm. 0.25 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.
6.75x4.5 mm. 0.88 ct.
7x5 mm. 1.00 ct.
7.5x5.3 mm. 1.25 ct.
7.5x5.5 mm. 1.50 ct.
8x6 mm. 1.75 ct.
8.5x6.5 mm. 2.00 ct.
9x7 mm. 2.50 ct.
MM Size Carat Weight
9.3x7.5 mm. 3.00 ct.
9.5x7.5 mm. 3.21 ct.
9.75x7 mm. 3.50 ct.
9.9x7.8 mm. 3.79 ct.
10x8 mm. 4.00 ct.
10.5x8.5 mm. 4.50 ct.
11x9 mm. 5.00 ct.
12x8 mm. 5.34 ct.
12x10 mm. 6.00 ct.
14x8 mm. 6.25 ct.
14x9 mm. 6.38 ct.
14x10 mm. 8.48 ct.
13x11 mm. 9.13 ct.
14x12 mm. 11.26 ct.
16x12 mm. 14.22 ct.
Heart Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
4 mm. 0.25 ct.
5 mm. 0.50 ct.
6 mm. 0.75 ct.
6.5 mm. 1.00 ct.
7 mm. 1.25 ct.
7.5 mm. 1.50 ct.
7.7 mm. 1.75 ct.
8 mm. 2.00 ct.
8.5 mm. 2.50 ct.
9 mm. 3.00 ct.
10 mm. 3.50 ct.
10.5 mm. 4.00 ct.
11 mm. 4.50 ct.
11.5 mm. 5.00 ct.
MM Size Carat Weight
3.5 mm. 0.18 ct.
4 mm. 0.25 ct.
4.25 mm. 0.28 ct.
4.5 mm. 0.34 ct.
4.75 mm. 0.38 ct.
5 mm. 0.50 ct.
5.5 mm. 0.61 ct.
6 mm. 0.75 ct.
6.25 mm. 0.83 ct.
6.5 mm. 1.00 ct.
7 mm. 1.25 ct.
7.5 mm. 1.50 ct.
7.7 mm. 1.75 ct.
MM Size Carat Weight
8 mm. 2.00 ct.
8.5 mm. 2.50 ct.
9 mm. 3.00 ct.
10 mm. 3.50 ct.
10.5 mm. 4.00 ct.
11 mm. 4.50 ct.
11.5 mm. 5.00 ct.
12 mm. 5.66 ct.
13 mm. 7.88 ct.
14 mm. 9.38 ct.
15 mm. 10.79 ct.
16 mm. 13.27 ct.
18 mm. 15.33 ct.
Marquise Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
6x3 mm. 0.25 ct.
8x4 mm. 0.50 ct.
9x4.5 mm. 0.75 ct.
10x5 mm. 1.00 ct.
11x5.5 mm. 1.25 ct.
12x6 mm. 1.50 ct.
12.5x6.25 mm. 1.75 ct.
13x6.5 mm. 2.00 ct.
14x7 mm. 2.50 ct.
15x7 mm. 3.00 ct.
15x8 mm. 3.50 ct.
16.5x8.25 mm. 4.00 ct.
16.75x8.5 mm. 4.50 ct.
17x8.5 mm. 5.00 ct.
MM Size Carat 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.
9.5x4.7 mm. 0.85 ct.
MM Size Carat Weight
10x5 mm. 1.00 ct.
11x5.5 mm. 1.25 ct.
11.5x6 mm. 1.33 ct.
12x6 mm. 1.50 ct.
12.5x6.25 mm. 1.75 ct.
13x6.5 mm. 2.00 ct.
14x7 mm. 2.50 ct.
15x7 mm. 3.00 ct.
15x7.5 mm. 3.25 ct.
15x8 mm. 3.50 ct.
16x8 mm. 3.86 ct.
16.5x8.25 mm. 4.00 ct.
16.75x8.5 mm. 4.50 ct.
17x8.5 mm. 5.00 ct.
17.5x10 mm. 5.50 ct.
20x8 mm. 7.08 ct.
20x10 mm. 7.94 ct.
20x11 mm. 9.50 ct.
Oval Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
5x3 mm. 0.25 ct.
6x4 mm. 0.50 ct.
7x5 mm. 0.75 ct.
7.7x5.7 mm. 1.00 ct.
8x6 mm. 1.25 ct.
8.5x6.5 mm. 1.50 ct.
9x6.5 mm. 1.75 ct.
9x7 mm. 2.00 ct.
10x8 mm. 2.50 ct.
12x8 mm. 3.00 ct.
12x8.5 mm. 3.50 ct.
12.5x8.5 mm. 4.00 ct.
12.75x8.5 mm. 4.50 ct.
12x10 mm. 5.00 ct.
MM Size Carat Weight
3.6x2.7 mm. 0.10 ct.
4x3 mm. 0.15 ct.
4.5x3.5 mm. 0.20 ct.
5x3 mm. 0.25 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.
9x6.5 mm. 1.75 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.
12x8.5 mm. 3.50 ct.
11x9 mm. 3.85 ct.
12.5x8.5 mm. 4.00 ct.
12.75x8.5 mm. 4.50 ct.
12x10 mm. 5.00 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.
Pear Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
5x3 mm. 0.25 ct.
6x4 mm. 0.50 ct.
7x5 mm. 0.75 ct.
7.7x5.7 mm. 1.00 ct.
8x6 mm. 1.25 ct.
8.5x6.5 mm. 1.50 ct.
10x6 mm. 1.75 ct.
9x7 mm. 2.00 ct.
10x8 mm. 2.50 ct.
12x8 mm. 3.00 ct.
12x9 mm. 3.50 ct.
14x8 mm. 4.00 ct.
14.5x9 mm. 4.50 ct.
15x9 mm. 5.00 ct.
MM Size Carat 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. 1.75 ct.
8.7x6.7 mm. 1.80 ct.
9x7 mm. 2.00 ct.
10x8 mm. 2.50 ct.
11x7.50 mm. 2.61 ct.
11x8 mm. 2.70 ct.
12x8 mm. 3.00 ct.
MM Size Carat Weight
12x7 mm. 3.12 ct.
13x8 mm. 3.40 ct.
12x9 mm. 3.50 ct.
14x8 mm. 4.00 ct.
13x9 mm. 4.11 ct.
14x9 mm. 4.25 ct.
14.5x9 mm. 4.50 ct.
15x9 mm. 5.00 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.
Radiant Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
4.3x3 mm. 0.25 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. 1.75 ct.
8.2x6.2 mm. 2.00 ct.
9x7 mm. 2.50 ct.
9.5x7.5 mm. 3.00 ct.
10x8 mm. 3.50 ct.
10.2x8.2 mm. 4.00 ct.
10.5x8.5 mm. 4.50 ct.
11x9 mm. 5.00 ct.
MM Size Carat Weight
4.3x3 mm. 0.25 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. 1.75 ct.
8.2x6.2 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 Size Carat Weight
10x8 mm. 3.50 ct.
10.2x8.2 mm. 4.00 ct.
10.5x8.5 mm. 4.50 ct.
11x9 mm. 5.00 ct.
12x9 mm. 6.06 ct.
11.5x10 mm. 6.45 ct.
13x9 mm. 6.54 ct.
13.2x9.2 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.
Asscher Diamond Size Chart

Want to know the actual size of a 1 carat diamond on a hand? Use our diamond size chart to understand the millimeter (mm) size of each diamond shape.

MM Size Carat Weight
3.25 mm. 0.25 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.
6.7 mm. 1.75 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. 4.00 ct.
9.25 mm. 4.50 ct.
9.5 mm. 5.00 ct.
MM Size Carat Weight
3.25 mm. 0.25 ct.
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.
6.7 mm. 1.75 ct.
7 mm. 2.00 ct.
7.5 mm. 2.50 ct.
MM Size Carat Weight
8 mm. 3.00 ct.
8.5 mm. 3.50 ct.
9 mm. 4.00 ct.
9.25 mm. 4.50 ct.
9.5 mm. 5.00 ct.
10 mm. 5.62 ct.
11 mm. 7.44 ct.
12 mm. 9.52 ct.
13 mm. 12.66 ct.