The Punishment of Tityus, a rock crystal intaglio by Giovanni Bernardi

This rock crystal intaglio depicts the punishment of Tityus, a giant in Greek mythology who tried to rape the goddess Leto and was banished by Zeus to Hades, there to have his liver eaten by birds of prey for eternity.The gem was engraved by Giovanni Bernardi da Castelbolognese (1494-1553), the design based on drawings made by Michelangelo for his friend Tommaso de' Cavalieri (now in the Royal Collection, Windsor Castle). Bernardi was famed for his work as a gem-cutter, specialising in rock crystal. The son of a goldsmith, he started work as a gem-cutter and medallist. Before 1530 he moved to Rome and worked under the patronage of Giulio de' Medici, Pope Clement VII (1523-34) and Cardinal Ippolito de' Medici (1511-35). He engraved this gem and two others for the Cardinal. It was much admired by the artist and historian Giorgio Vasari, when he saw it in the collections of Pier Luigi Farnese.Engraved gems, both antique and contemporary, were highly prized by collectors during the Renaissance. Princely collectors competed to acquire the best collections, and gems were often traded and presented as gifts. Skilled gem-cutters were able to produce superb original pieces as well as reproductions of antique gems; these then became widely known through the use of prints and were themselves reproduced, as gems and as plaquettes.