(Ring of) same as Polycrates' Ring. Polycrates, tyrant of Samos, was so fortunate in everything that Amasis, King of Egypt, advised him to part with something which he highly prized. Polycrates accordingly threw into the sea an engraved ring of extraordinary value. A few days afterwards, a fish was presented to the tyrant, in which the ring was found. Amasis now renounced all friendship with Polycrates, as a man doomed by the gods; and not long afterwards, a satrap, having entrapped the too fortunate despot, put him to death by crucifixion. —Herodotus, iii. 40.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894