This table shows the ring sizes conversion for different countries and diameters that correspond to those sizes. If you have any questions, please e-mail us at info@thefacetscollection.com

Size Diameter (in) Diameter (mm) British French German Japanese Swiss
0.5 31/64 12.1 A
1 1/2 12.5 B     1  
1.5 33/64 12.9 C        
2 17/32 13.3 D 41 1/2 13 1/2 2 1 1/2
2.5 35/64 13.7 E 42 3/4 13 3/4 3 2 3/4
3 9/16 14.1 F 44 14 4 4
3.5 37/64 14.5 G 45 1/4 14 1/2 5 5 5/4
4 19/32 14.9 H 1/2 46 1/2 15 7 7 3/4
4.5 39/64 15.3 I 1/2 47 3/4 15 1/4 8 9
5 5/8 15.8 J 1/2 50 15 3/4 9 10
5.5 41/64 16.2 L 51 3/4 16 11 11 3/4
6 21/32 16.6 M 52 3/4 16 1/2 12 12 3/4
6.5 43/64 17.0 N 54 17 13 14
7 11/16 17.4 O 55 1/4 17 1/4 14 15 1/4
7.5 45/64 17.8 P 56 1/2 17 3/4 15 16 1/2
8 23/32 18.2 Q 57 3/4 18 16 17 3/4
8.5 47/64 18.6 R 58 1/2 18 1/2 17 18 3/4
9 3/4 19.0 S 60 19 18 19 /34
9.5 49/64 19.4 T 1/2 61 1/2 19 1/2 20 21
10 25/32 19.8 T 1/2 62 1/4 20 21 21 3/4
10.5 51/64 20.2 U 1/2 63 20 1/4 22 23 1/4
11 13/16 20.6 V 1/2 64 1/2 20 3/4 23 24
11.5 53/64 21.1 X 66 1/4 21 1/4 24 25 3/4
12 27/32 21.5 Y 67 1/2 21 1/4 25 27 1/2
12.5 55/64 21.7 Z 68 3/7 21 3/4 26 28 3/4
13 7/8 22.3 Z+1 70 22 27 29 3/4
13.5 57/64 22.7 Z+2     29  
14 29/32 23.1 Z+3     31  
14.5 59/64 23.5 Z+4     32  
15 15/16 23.9 Z+5     33