Shell coin, Boiken, Papua New Guinea Diameter: 25.5 cm Flamingo shell. Carved from a thick marine shell, this ring served as a prestige currency used in ceremonial exchanges, marriage alliances, and customary compensation. It attests to the importance of shell money in the traditional value systems of the northern coast of New Guinea. Provenance: Holger Braun Gallery, Germany. See: Christie’s, Paris, December 10, 2003, lot 47 for a comparable example.