The London Lounge

In addition to the crested ring on the little finger of the left hand I've noticed several people wearing a thinner one-usually put on after the larger signet ring.The Prince of Wales is a example- can anyone shed any light on this second ring.?

'Could be a wedding band. Though, if I remember correctly, a man's wearing his wedding band on the little finger of the left hand was an American custom, one that disappeared a few generations ago (I think I remember reading that American soldiers in the First World War were struck by and later emulated the European custom of wearing the wedding band on the ring finger instead of the little finger).