Millimeter (mm) to Carat (ct) Gemstone Conversion Chart

Carat Size

Round/Square
Brilliant/Princess

Pear

Marquise

Oval

Emerald

Heart

Trillion

0.25

4.1

6 x 3

5 x 3

5 x 3

4 x 4

4.5 x 4.5 x 4.5

0.50

5.2

6 x 4

8 x 4

6 x 4

6 x 4

5 x 5

6 x 6 x 6

0.75

5.8

7 x 5

9 x 4.5

6.5 x 4.5

6 x 6

1.00

6.5

8 x 5

10 x 5

7 x 5

7 x 5

6.5 x 6.5

1.25

7.0

7.5 x 5.5

1.50

7.4

9 x 6

11 x 5.5

8 x 6

8 x 6

7 x 7

7 x 7 x 7

2.00

8.2

10 x 7

12 x 6

8.5 x 6.5

8.5 x 6.5

8 x 8

8 x 8 x 8

2.50

8.8

12 x 7

13 x 6.5

9 x 7

9 x 7

8.5 x 8.5

9 x 9 x 9

3.00

9.4

12 x 8

14 x 7

10 x 8

10 x 8

9 x 9

10 x 10 x 10

3.50

10.0

13 x 8

14 x 7.5

10 x 8.5

9.5 x 9.5

4.00

10.04

14 x 8

16 x 8

11 x 9

11 x 9

10 x 10

4.50

10.80

14.5 x 9

11 x 9.5

10.5 x 10.5

5.00

11.20

15 x 9

16 x 8.5

12 x 10

12 x 10

11 x 11