Sheffield researchers replicate ancient colour‑changing glass of Lycurgus Cup
University of Sheffield technicians have reproduced the 1,600‑year‑old colour‑shift effect of the Lycurgus Cup, confirming a repeatable glass recipe. The Roman cup, dated to around 400 CE, changes from jade green in reflected light to ruby red in transmitted light because of gold and silver nanoparticles smaller than visible wavelengths. The team, prompted by project manager Christina Metcalfe for the university’s LightFest, says the new glass matches the original’s optical properties, offering a reliable method to study the ancient technique.