1728 E. Chambers at Seal The Pope has two Kinds of Seals: The first used in Apostolical Briefs, and private Letters, &c. called, the Fisherman's Ring. This is a very large Ring, wherein is represented St. Peter, drawing his Nets full of Fishes.
1877 W. Jones 198 The ‘Fisherman's Ring’ is the Pope's ring of investiture.