Sheffield Technician Coaxes Color-Changing Roman Glass Back to Life After 1,600 Years

SHEFFIELD, ENGLAND — A technician at the University of Sheffield has reproduced, for the first time in some 1,600 years, the color-changing effect of the Roman Lycurgus Cup, according to a press release reported by Ancient Pages.

The cup, which dates to the 4th century AD and is kept in the British Museum, is made of dichroic glass. It appears jade green in reflected light and ruby red when light passes through it. The report states it is one of about 40 surviving glass cage cups from the period, and the only one with this effect. In 2022, it says, an international panel of artists and conservators named it among the seven glass wonders of the world.

Nobody knows precisely how the Romans managed it, the article says, though experts believe tiny amounts of gold and silver formed nanoparticles smaller than the wavelengths of light. A consistent, repeatable recipe has long proved elusive.

The task was taken up after Project Manager Christina Metcalfe set a challenge for the University's LightFest in 2025. Dr Lisa Hollands, who says she has worked with glass for more than 25 years, consulted Roman glass expert Professor Caroline Jackson and devised a base glass from modern materials. She then ran many experiments with different furnaces, starting materials and oxygen levels, and even added sugar, before arriving at a glass that looked opaque green by reflected light and red when lit from behind.

Glass artist Elliot Walker, a winner of Netflix's Blown Away, was commissioned to make a sculpture from the recipe. The release describes it as a blend of the Lycurgus story and the Farnese Atlas, with the globe replaced by a cup. Hollands remarked that the Romans might laugh at her efforts.

The glass itself will mostly serve decorative ends, the report says, but the knowledge gained is expected to feed into new photonic materials and advanced glasses for radioactive waste management.