This extraordinary cup is the only surviving complete example made from dichroic glass, which changes colour when held up to the light. When light is shone through the body of the cup it turns from opaque green to a glowing translucent red. The glass contains tiny amounts of colloidal gold and silver, which give it these unusual optical properties.

The cup is also the only figural example of a vessel known as a ‘cage-cup’. First a thick glass blank was blown or cast, then cut and ground away until the figures were left in high relief. Sections of the figures are almost free-standing and connected only by ‘bridges’ to the surface of the vessel.

The relief depicts an episode from the myth of Lycurgus, a king of the Thracians, who attacked the god Dionysos and one of his female followers. He was punished by being entrapped in the branches of a vine.



Probably made in Rome, 4th century ad
Ht 16.50 cm (with modern metal mounts)
D. 13.20 cm
Purchased with the aid of the Art Fund