Ring size
7 diameter 17.4 mm perimeter 52 mm
8 diameter 18.2 mm perimeter 55 mm
9 diameter 19 mm perimeter 57 mm
10 diameter 20.2 mm perimeter 59.8 mm
11 diameter 20.8 mm perimeter 63.2 mm
12 diameter 21.5 mm perimeter 67.5 mm
13 diameter 22.3 mm perimeter 70 mm