1diamondjewelry

UK

Average

Average

Circumference in mm

USA/Canada

China / HK

Diameter

Diameter

(mm)

(inches)

1

B

1

12.37

0.487

38.8418

2

D

4

13.25

0.52

41.605

2 ½

E

5

13.75

0.536

43.175

3

F

6

14

0.553

43.96

3 ½

G-G-½

7

14.5

0.569

45.53

4

H-½

9

15

0.585

47.1

4 ½

I-½

10

15.25

0.601

47.885

5

J ½

11

15.75

0.618

49.455

5 ½

L

12

16

0.634

50.24

6

M

13

16.5

0.65

51.81

6 ½

N

14

17

0.666

53.38

7

O

15

17.25

0.683

54.165

7 ½

P

16

17.75

0.699

55.735

8

Q

17

18

0.716

56.52

8 ½

Q-½-R

18 ~ 19

18.5

0.732

58.09

9

R-½-S

20

19

0.748

59.66

9 ½

S-½-T

22

19.5

0.764

61.23

10

T-½

23

20

0.781

62.8

10 ½

U-½

24

20.25

0.797

63.585

11

V-½

25

20.75

0.814

65.155

11 ½

W-½-X

26

21

0.83

65.94

12

Y

27~28

21.5

0.846

67.51

12 ½

Z

21.75

0.862

68.295

13

22

0.879

69.08

UK

Average

Average

Circumference in mm

USA/ Canada

China / HK

Diameter

Diameter

(mm)

(inches