The size range of Chinese rings is 4-26, that of European rings is 44-61, and that of American rings is 5-12. Therefore, the size of No. 15 belongs to China. Please check the ring size comparison table of Chinese Mainland or Hong Kong version.
Mainland version ring size comparison chart
According to the table below, the circumference of the mainland version corresponding to ring size 15 is 55mm and the diameter is 17.5mm.
Hong Kong Ring Size Comparison Table
According to the table below, ring size 15 corresponds to a Hong Kong version with a circumference of 57mm and a diameter of 17.3mm.
