Decorated with the arms of popes or cardinals, papal rings of the fifteenth century were made of gilt bronze or copper set with glass or crystal bezels, and distinguished by their great size. Their exact function remains a mystery, although it is thought they may have been given as credentials to an envoy from the pope or cardinal to the king, used as a sign of authentication for the wearer during their journey. Comparable papal rings are in the British Museum (inv. 1888,1201.3) and Victoria & Albert Museum (inv. 664-1871 and 667-1871).