British Museum The Lycurgus Cup 01 15022019 4376

The Lycurgus Cup, a cage-cup ( diatreta ) made of dichroic glass, Late Roman Empire, 300s AD. Gilded silver rim and foot were probably added in the late 1700s.
Information provided by the British Museum : "its glass contains tiny amount of gold and silver which cause it to turn from opaque green to translucent red when light is shone through."

Room 41, British Museum.