Diamond mm to carat conversion chart

The table sets out the approximate relationship between the size of a diamond and its Carat weight.

Round Stones

 
Milimeters Carat weight Points

1.0

0.005

0.5

1.3

0.01

1

1.5

0.02

1.5

1.7

0.02

1

1.8

0.03

2.5

2.0

0.03

3

2.1

0.04

3.5

2.2

0.04

4

2.4

0.05

5

2.5

0.06

6

2.7

0.07

7

2.8

0.08

8

2.9

0.09

9

3.0

0.10

10

3.1

0.11

11

3.2

0.12

12

3.3

0.14

14

3.4

0.15

15

3.5

0.16

16

3.6

0.17

17

3.7

0.18

18

3.8

0.20

20

3.9

0.22

22

4.0

0.25

25

4.2

0.30

30

4.4

0.33

33

4.5

0.35

35

4.6

0.38

38

4.8

0.40

40

5.0

0.50

50

5.4

0.60

60

5.5

0.63

63

5.6

0.65

65

6.0

0.75

75

6.4

0.95

95

6.6

1.00

100

6.8

1.17

117

7.0

1.25

125

7.2

1.33

133

7.5

1.55

155

7.8

1.75

175

8.0

2.00

200

8.4

2.15

215

8.6

2.25

225

9.0

2.75

275

9.4

3.00

300

9.6

3.15

315

9.8

3.35

335

10.0

3.50

350

10.2

3.75

375

10.4

4.00

400

10.6

4.25

425

10.8

4.50

450

11.0

4.75

475

11.2

5.00

500

12.0

6.50

650

Oval Cut

 
Milimeters Carat weight Points
4 x 3

0.20

20

5 x 3

0.25

25

5 x 3.5

0.33

33

5 x 4

0.40

40

6 x 4

0.50

50

6.5 x 4.5

0.65

65

7 x 5

0.75

75

7.5 x 5.5

1.00

100

8 x 6

1.25

125

8.5 x 6.5

1.50

150

9 x 6

1.75

175

9 x 7

2.00

200

9.5 x 7.5

2.50

250

10 x 8

3.00

300

10 x 8.5

3.50

350

11 x 9

4.00

400

11 x 9.5

4.50

450

12 x 10

5.00

500

Marquise Cut

 
Milimeters Carat weight Points
3.5 x 1.5

0.07

7

4 x 2

0.10

10

5 x 2

0.20

20

5 x 3

0.22

22

5.5 x 2.5

0.25

25

6 x 6

0.30

30

7 x 3

0.35

35

7 x 3.5

0.38

38

7 x 4

0.40

40

8 x 4

0.50

50

8.5 x 4.5

0.65

65

9 x 4

0.70

70

9 x 4.5

0.75

75

9 x 5

0.80

80

9.5 x 4.5

0.85

85

10 x 4.75

1.00

100

10 x 5

1.25

125

11 x 5

1.50

150

11 x 5.5

1.65

165

12 x 6

2.00

200

13 x 5.5

2.50

250

13 x 6

2.65

265

14 x 6.5

2.87

287

14 x 7

3.00

300

15 x 7

3.75

375

16 x 8

4.50

450

18 x 9

7.00

700

20 x 10

10.00

1000

Princess Cut

 
Milimeters Carat weight Points

2.0

0.06

6

2.3

0.08

8

2.5

0.10

10

2.8

0.13

13

3.0

0.15

15

3.3

0.20

20

3.5

0.23

23

3.8

0.25

25

4.0

0.30

30

4.4

0.35

35

4.5

0.40

40

4.8

0.50

50

5.0

0.63

63

5.3

0.75

75

5.5

1.00

100

6.0

1.25

125

7.0

1.60

160

8.0

2.25

225

Emerald Cut

 
Milimeters Carat weight Points
4 x 3

0.20

20

5 x 3

0.25

25

6 x4

0.50

50

6.5 x 4.5

0.75

75

7 x 5

1.00

100

8 x 6

1.50

150

8.5 x 6.5

2.00

200

9 x 7

2.50

250

10 x 8

3.00

300

11 x 9

4.00

400

12 x 10

5.00

500

Pear Cut

 
Milimeters Carat weight Points
4 x 2

0.20

20

5 x 3

0.30

30

6 x 4

0.50

50

7 x 5

0.75

75

8 x 5

1.00

100

9 x 6

1.50

150

10 x 7

2.00

200

12 x 7

2.50

250

12 x 8

3.00

300

13 x 8

3.50

350

14 x 8

4.00

400

15 x 9

5.00

500

Heart Shaped Stones

 
Milimeters Carat weight Points
4×4

0.25

25

5×5

0.50

50

5.5×5.5

0.65

65

6×6

0.75

75

6.5×6.5

1.00

100

7×7

1.50

150

8×8

2.00

200

8.5×8.5

2.50

250

9×9

3.00

300

9.5×9.5

3.50

350

10×10

4.00

400

10.5×10.5

4.50

450

11×11

5.00

500

Tapered Baguette Cut Stones
Milimeters Carat weight Points
3x1x0.05

0.04

4

3x1x5.1

0.06

6

3.5×1.5×1

0.09

9

3.5×2.5×1

0.15

15

4x2x1

0.12

12

4.5x2x1

0.15

15

5x2x1.5

0.20

20

Baguette Cut
Milimeters Carat weight Points
3×1.5

0.05

5

3×2

0.09

9

3.5×2

0.11

11

4×2

0.16

16

5×2

0.20

20

5×2.5

0.25

25

5×3

0.30

30

6×2

0.30

30

6×3

0.40

40

6×4

0.60

60