A University of Sheffield technician has successfully recreated the remarkable colour-changing glass used in a 4th-century Roman masterpiece for the first time in 1,600 years.

Dr Lisa Hollands, from the University of Sheffield's School of Chemical, Materials and Biological Engineering, replicated the dichroic glass that forms the Lycurgus Cup, a world-renowned artefact housed in the British Museum. The glass shifts from jade green in reflected light to ruby red in transmitted light, depending on where the light source is positioned.

The Lycurgus Cup is one of only 40 surviving glass cage cups from the period and is the only one exhibiting this colour-changing effect. In 2022, an international panel of artists and conservators recognised it as one of the seven glass wonders of the world.

How the ancient technique was solved

Experts believe the Romans achieved the effect by adding tiny amounts of gold and silver, which formed layered nanoparticles thousands of times smaller than a grain of sand. Because these nanoparticles are smaller than the wavelengths of light, they absorb light strongly and display vibrant colours depending on their size and shape.

Many have attempted to reproduce the effect with varying success, but establishing a consistent, repeatable recipe proved elusive until now.

Dr Hollands worked with leading Roman glass expert Professor Caroline Jackson to research glass from the period and developed a base glass using modern materials to mimic what the Romans might have used. She then conducted painstaking experiments with different furnace types, starting materials, oxygen levels and other variables to achieve the effect.

"I've studied and worked with glass for over 25 years, so I used the knowledge and experience I've gained, coupled with a modern scientific understanding of what I was trying to achieve," Dr Hollands said.

"Although if the Romans could have seen me experimenting, they'd probably laugh and ask: 'Why does she not know how to make this?'"

After numerous trials, Dr Hollands developed a glass recipe that appeared opaque green in reflected light and red when a light was shone through it.

Contemporary sculpture on display

The initial piece was exhibited at LightFest, an event held in Sheffield by the Molecular Photonic Breadboards project in partnership with the Universities of Sheffield and Bristol and funded by the Engineering and Physical Sciences Research Council.

Glass artist Elliot Walker, winner of Netflix's Blown Away series 2, was commissioned to create a contemporary sculpture using Dr Hollands' recipe. Walker created the piece in the Sheffield melting shop, blending the classical form of the original Lycurgus Cup with the story of Lycurgus from Greek mythology and inspired by the Farnese Atlas sculpture.

"It is a very rare thing to have the opportunity to work with glass developed from ancient mixtures and recipes, and it is always a very exciting one. You can really get an idea of how the glass makers of the past would have adapted to this sort of glass; it's like shaking their hands," Walker said.

The sculpture will debut at the University of Sheffield's Festival of the Mind from 6–15 November 2026, before moving to permanent display in the University's Turner Museum of Glass under lighting designed to demonstrate its colour-changing properties.