Technician cracks 1,600-year-old mystery to replicate color-changing effect of Roman glass masterpiece

The Lycurgus Cup, a world-renowned 4th-century A.D. artifact housed in the British Museum, is constructed of "dichroic" glass that shifts from jade green in reflected light to ruby red in transmitted light. This means that depending on where the light source is positioned, observers can see the cup displayed in two distinctive, contrasting colors.