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The Lycurgus Cup is a Roman glass 4th-century cage cup made of a dichroic glass, which shows a different colour depending on whether or not light is passing through it: red when lit from behind and green when lit from in front.

It is the only complete Roman glass object made from this type of glass, and the one exhibiting the most impressive change in colour; it has been described as "the most spectacular glass of the period, fittingly decorated, which we know to have existed". The cup is also a very rare example of a complete Roman cage-cup, or diatretum, where the glass has been painstakingly cut and ground back to leave only a decorative "cage" at the original surface-level. Most cage-cups have a cage with a geometric abstract design, but here there is a composition with figures, showing the mythical King Lycurgus, who (depending on the version) tried to kill Ambrosia, a follower of the god Dionysus (Bacchus to the Romans). She was transformed into a vine that twined around the enraged king and restrained him, eventually killing him. Dionysus and two followers are shown taunting the king. The cup is the "only well-preserved figural example" of a cage cup. The dichroic effect is achieved by making the glass with tiny proportions of nanoparticles of gold and silver dispersed in colloidal form throughout the glass material. The glass-makers may not even have known that gold was involved, as the quantities involved are so tiny; they may have come from a small proportion of gold in any silver added (most Roman silver contains small proportions of gold), or from traces of gold or gold leaf left by accident in the workshop, as residue on tools, or from other work.

Corning Glass Works has reproduced a blank of a material of similar chemical composition and internal structure, which displays under reflected and transmitted light the same "Lycurgus effect" of green to red colour change as the Lycurgus cup material does. This effect, like in the original Lycurgus cup is due to small amounts of silver and gold nanoparticles, of the proper size and shapes, embedded in the 3D printable material.

Other depictions of the story tend to either depict Lycurgus attacking Ambrosia, often with a double-headed axe, while her companions rush to her aid, or Lycurgus alone, entangled in the vine.

The foot continues the theme of the cup with open-work vine leaves, and the rim has leaf forms that lengthen and shorten to match the scenes in glass. In 1958 the foot was removed by British Museum conservators, and not rejoined to the cup until 1973. The cup forms part of the museum's Department of Prehistory and Europe rather than the Greece and Rome Department, and was previously on display, lit from behind, in Room 50. In 2015 it was on display with the new display of the Rothschild donation of the Waddesdon Bequest in Room 2A, with a changing internal lighting source that shows the colour change very effectively, though only one side of the cup can be seen. While Room 41, where it was then displayed, was closed for refurbishment, from November 2012 to August 2013 it was on display with other British Museum pieces at the Art Institute of Chicago's Jaharis Galleries of Greek, Roman and Byzantine Art, where it was very effectively displayed in a free-standing case, lit from above with changing light so that the colour change was clearly visible. It is considered able to travel to important exhibitions and in 2008 was exhibited in "Reflecting Antiquity, Modern Glass Inspired by Ancient Rome" at the Corning Museum of Glass in Corning, New York, in 2003 at the Hayward Gallery in London in "'Saved! 100 Years of the National Art Collections Fund", and in 1987 in "Glass of the Caesars" in the British Museum, Cologne, Milan, and Rome.

Quick Facts

• Corning Glass Works has reproduced a blank of a material of similar chemical composition and internal structure, which displays under reflected and transmitted light the same "Lycurgus effect" of green to red colour change as the Lycurgus cup material does.
• The cup is also a very rare example of a complete Roman cage-cup, or diatretum, where the glass has been painstakingly cut and ground back to leave only a decorative "cage" at the original surface-level.
• Most cage-cups have a cage with a geometric abstract design, but here there is a composition with figures, showing the mythical King Lycurgus, who (depending on the version) tried to kill Ambrosia, a follower of the god Dionysus (Bacchus to the Romans).
• The cup is the "only well-preserved figural example" of a cage cup.
• This effect, like in the original Lycurgus cup is due to small amounts of silver and gold nanoparticles, of the proper size and shapes, embedded in the 3D printable material.

Source material: Wikipedia - "Lycurgus Cup". Adapted and summarized for DiscoverScroll. Original contributors are credited through the linked Wikipedia article. Read original on Wikipedia. CC BY-SA 4.0. Changes were made from the original.