Ring of the Fisherman cardinal. Ring of the Fisherman The Ring of the Fisherman (Latin: "Annulus Piscatoris"; Italian: "Anello Piscatorio"), also known as the Piscatory Ring, is an official part of the regalia worn by the Pope, who is head of the Catholic Church and successor of Saint Peter who was a fisherman by trade. It used to feature a bas-relief of Peter fishing from a boat, a symbolism derived from the tradition that the apostles were "fishers of men" (Mark 1:17). The Fisherman's Ring is a signet used until 1842 to seal official documents signed by the Pope. A letter written by Pope
Localization of a ring "S" to be multiplicatively closed in what follows. In the case "R" is an integral domain there is an easy construction of the localization. Since the only ring in which 0 is a unit is the trivial ring {0}, the localization "R*" is {0} if 0 is in "S". Otherwise, the field of fractions "K" of "R" can be used: we take "R*" to be the subset of "K" consisting of the elements of the form "r"/"s" with "r" in "R" and "s" in of "S"; as we have supposed "S" multiplicatively closed, "R"* is a subring. The standard embedding