The Lycurgus Cup is a late Roman glass vessel that changes color with lighting. It appears green in reflected light and red when light passes through it. The cup is also a carved cage cup with a mythological scene surrounding its inner vessel.
Material and color
The glass contains extremely small particles of gold and silver that affect how it scatters light. Describing the effect as ancient nanotechnology can be a useful modern comparison, but it should not imply that Roman makers used present-day atomic theory or laboratory language.
The consistency of the color effect suggests controlled specialist production, though the exact workshop method is not recorded. The silver-gilt rim and foot are later mounts added to the ancient glass.
Lycurgus and Dionysus
The carved scene shows King Lycurgus entangled by a vine after opposing Dionysus. Figures connected with the god close around him. The myth suits a drinking vessel because it warns about resistance to the power of wine and the god who governs it.
The cup is generally dated to the fourth century CE. It is the only complete surviving Roman cage cup made from this type of dichroic glass, which explains both its scientific interest and its rarity as an artwork.