DIAMOND SIZE

Diamond Sizes in MM

If you know your ring size but have a different number than those used in Belgium (ISO 8653:2016, which defines the number in terms of internal circumference), use the table below to convert your size. We also recommend cross-referencing your ring size by measuring the ring’s internal diameter and/or internal circumference. Wondering what a 1 carat round diamond looks like on a hand? Our round diamond size chart will help you convert millimeter (mm) size to carat size for round cut diamonds.
Visit our Select a Diamond page to explore our extensive collection of loose diamonds. Find the perfect diamond that matches your style and budget, and take the first step towards creating your dream jewelry piece today!

Diamond Sizes in MM

ROUND MM SIZEROUND CARAT WEIGHTBLACK DIAMONDS CT. WEIGHT
0.8 mm.0.0025 ct.0.00
1 mm.0.005 ct.0.01
1.1 mm.0.0067 ct.0.01
1.2 mm.0.009 ct.0.01
1.25 mm.0.01 ct.0.01
1.3 mm.0.01 ct.0.01
1.5 mm.0.015 ct.0.02
1.75 mm.0.02 ct.0.02
1.8 mm.0.025 ct.0.03
2 mm.0.03 ct.0.04
2.2 mm.0.04 ct.0.05
2.5 mm.0.06 ct.0.07
2.75 mm0.08 ct.0.10
3 mm.0.10 ct.0.12
3.25 mm.0.14 ct.0.17
3.5 mm.0.17 ct.0.20
3.75 mm.0.21 ct.0.25
4 mm0.25 ct.0.33
4.25 mm.0.28 ct.0.36
4.5 mm.0.36 ct.0.47
4.75 mm.0.44 ct.0.57
5.0 mm.0.50 ct.0.65
5.25 mm.0.56 ct.0.73
5.5 mm.0.66 ct.0.89
5.75 mm.0.75 ct.1.01
6 mm.0.84 ct.1.20
6.25 mm.0.93 ct.1.30
6.5 mm.1.00 ct1.40
6.8 mm.1.25 ct.1.80
7 mm.1.30 ct.1.90
7.3 mm.1.50 ct.2.10
7.5 mm.1.67 ct.2.40
7.75 mm.1.75 ct.2.50
8 mm.2.00 ct.2.80
8.25 mm.2.11 ct.3.00
8.5 mm.2.43 ct.3.50
8.7 mm.2.50 ct.3.50
9 mm.2.75 ct.3.90
9.1 mm.3.00 ct.4.20
9.5 mm.3.35 ct.4.70
9.75 mm.3.61 ct.5.10
10 mm.3.87 ct.5.50
10.25 mm.4.16 ct.5.50
10.5 mm.4.41 ct.5.80
10.75 mm.4.57 ct.6.00
11 mm.4.91 ct.6.40
11.25 mm.5.49 ct.7.20
11.5 mm.5.85 ct.7.70
12 mm.6.84 ct.8.90
12.25 mm.7.26 ct.9.50
12.5 mm.7.36 ct.9.60
12.75 mm.7.52 ct.9.80
13 mm.8.51 ct.11.10
13.5 mm.9.53 ct.12.40
14 mm.10.49 ct.13.70
15 mm.12.89 ct.16.80
16 mm.16.06 ct.20.90

Princess Diamond Sizes

Princess MM SizePrincess Weight (ct)
1.5 mm.0.02
1.75 mm.0.03
2 mm.0.06
2.25 mm.0.08
2.5 mm.0.10
2.75 mm.0.13
3 mm.0.18
3.25 mm.0.26
3.5 mm.0.29
3.75 mm.0.31
4 mm.0.39
4.25 mm.0.44
4.5 mm.0.50
4.75 mm.0.64
5 mm.0.75
5.25 mm.0.90
5.5 mm.1.00
5.75 mm.1.11
6 mm.1.25
6.25 mm.1.39
6.5 mm.1.50
6.75 mm.1.75
7 mm.2.00
7.25 mm.2.01
7.5 mm.2.50
7.75 mm.2.74
8 mm.3.00
8.25 mm.3.24
8.5 mm.3.67
8.75 mm.4.10
9 mm.4.12
9.5 mm.5.09
9.75 mm.5.36
10 mm.5.62
10.25 mm.5.76
10.5 mm.5.99
11 mm.7.44
11.5 mm.9.44
12 mm.9.52

Cushion Diamond Sizes

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

Oval Diamond Sizes

Oval MM SizeOval Weight (ct)
4.5×3.5 mm.0.25
5×3 mm.0.25
5.5×3.5 mm.0.40
5×4 mm.0.42
6×4 mm.0.65
6×5 mm.0.79
6.5×4.5 mm.0.85
7×5 mm.1.00
7.7×5.7 mm.1.40
8×6 mm.1.80
9×6 mm.2.00
8.5×6.5 mm.2.10
9×7 mm.2.80
10×8 mm.3.50
10.5×8.5 mm.4.10
12×8 mm.4.20
11×9 mm.5.40
12×10 mm.7.10
14×10 mm.8.20
13×11 mm.8.50
14×12 mm.11.50
15×12 mm.12.30
16×12 mm.13.10
16×14 mm.16.70
18×13 mm.18.10
20×15 mm.21.00

Emerald Diamond Sizes

Emerald MM SizeEmerald Weight (ct)
3×2 mm.0.10
3.5×2 mm.0.12
4×2 mm.0.15
4×3 mm.0.20
5×3 mm.0.29
5.5×3.5 mm.0.46
6×4 mm.0.50
6.5×4.5 mm.0.75
6.7×4.5 mm.0.88
7×5 mm.1.00
7.3×5.3 mm.1.25
7.5×5.5 mm.1.50
8×6 mm.1.75
8.5×6.5 mm.2.00
9×7 mm.2.50
10×7.5 mm.3.00
9.5×7.5 mm.3.21
10×8 mm.3.79
11×9 mm.5.21
12×8 mm.5.34
12×10 mm.6.00
14×8 mm.6.25
13×9 mm.6.38
14×10 mm.8.48
13×11 mm.9.13
14×12 mm.11.26
16×12 mm.14.22

Heart Diamond Sizes

Heart MM SizeHeart Weight (ct)
3.5 mm.0.18
4 mm.0.25
4.25 mm.0.28
4.5 mm.0.34
4.75 mm.0.38
5 mm.0.50
5.5 mm.0.61
6 mm.0.75
6.25 mm.0.83
6.5 mm.1.00
7 mm.1.25
7.5 mm.1.50
8 mm.2.00
8.5 mm.2.50
9 mm.3.00
10 mm.3.50
11 mm.4.41
12 mm.5.66
13 mm.7.88
14 mm.9.38
15 mm.10.79
16 mm.13.27
18 mm.15.33

Pear Diamond Sizes

Pear MM SizePear Weight (ct)
3×2 mm.0.13
4×2.5 mm.0.18
4×3 mm.0.21
5×3 mm.0.25
5×4 mm.0.35
6×4 mm.0.50
6.5×4.5 mm.0.60
7×5 mm.0.75
7.5×5.5 mm.0.85
7.7×5.7 mm.1.00
8.5×6.5 mm.1.50
8.7×6.7 mm.1.80
9×7 mm.2.00
11×7.50 mm.2.61
13×8 mm.2.98
11×8 mm.3.00
12×8 mm.3.00
12×7 mm.3.12
12×9 mm.3.44
14×8 mm.3.47
13×9 mm.4.11
14×9 mm.4.25
15×9 mm.5.06
14×10 mm.5.41
13×11 mm.5.65
15×10 mm.5.75
16×9 mm.5.86
16×10 mm.6.27
17×10 mm.6.46
15×11 mm.7.36
18×11 mm.8.14
16×12 mm.8.99
18×12 mm.9.35
18×13 mm.10.21

Marquise Diamond Sizes

Marquise MM SizeMarquise Weight (ct)
3×1.5 mm.0.03
3.5×1.75 mm.0.07
3.5×2 mm.0.07
4×2 mm.0.10
3.75×1.75 mm.0.11
4.25×2.25 mm.0.12
5×2.5 mm.0.14
5.5×2.75 mm.0.16
5.5×3 mm.0.18
5×3 mm.0.20
6.5×3 mm.0.23
6×3 mm.0.25
7×3 mm.0.30
7.5×3.5 mm.0.33
7×4 mm.0.34
8×4 mm.0.50
8.75×4.25 mm.0.70
9×4.5 mm.0.75
9.5×4.7 mm.0.85
10×5 mm.1.00
11×5.5 mm.1.25
11.5×6 mm.1.33
12×6 mm.1.50
13×6.5 mm.2.00
14×7 mm.2.50
15×7 mm.3.00
14×8 mm.3.00
15×7.5 mm.3.25
15×8 mm.3.44
16×8 mm.3.86
16×8 mm.3.86
16.5×8.25 mm.4.00
17×8.5 mm.4.88
17.5×10 mm.5.50
20×8 mm.7.08
20×10 mm.7.94
20×11 mm.9.50

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