🌈 Magic Color-Changing Roman Glass

Dalya Alberge at The Guardian: Depending on where a light source is positioned, the Lycurgus Cup changes colour, from jade green under normal lighting to ruby red when lit from behind – an astonishing feat of optical engineering that has confounded historians and glass-makers for centuries. Now scientists from the University of Sheffield have replicated its remarkable optical behaviour, using an ancient recipe derived from a fragment of the Roman “dichroic” (two-coloured) original. Don't miss the video embedded in the article. The extent to which the colors change is remarkable, and it's quite beautiful.