University of Sheffield technician reproduces Lycurgus Cup's green-to-red dichroic glass with modern materials
Dr. Lisa Hollands developed a glass that looks green in reflected light and red when lit from behind, though the sample does not establish the Romans' exact recipe.
A technician at the University of Sheffield, Dr. Lisa Hollands, has developed a glass that reproduces the color-changing effect of the Lycurgus Cup, a Roman vessel made in the fourth century AD, SciTechDaily reports. The sample looks opaque green under reflected light and turns red when illuminated from behind scitechdaily.com
SciTechDailyscitechdaily.comOpen source ↗. The work was done for the university's LightFest in 2025.
The cup is kept in the British Museum and is made of dichroic glass, whose appearance depends on whether light reflects from the surface or passes through the material. It is one of only 40 surviving Roman glass cage cups and the only surviving example known to show this effect. In 2022 an international panel of artists and conservators named it one of the seven glass wonders of the world.
How the color effect arises
Scientists believe the effect comes from small amounts of gold and silver that Roman craftspeople added to the glass. Under the right conditions these metals form layered nanoparticles. Because the particles are smaller than the wavelengths of visible light, they absorb light strongly, and the resulting colors depend on their size and shape. The exact techniques of the Roman glassmakers remain unknown, and earlier attempts at reproduction had varying success.
Recipe and sculpture
Hollands worked with Roman glass expert Professor Caroline Jackson and developed a base glass from modern materials intended to mimic what the Romans might have used. The harder part was introducing small amounts of gold and silver in the right form. She tried different furnaces, starting materials and oxygen levels, and tested the addition of sugar scitechdaily.com
SciTechDailyscitechdaily.comOpen source ↗. The sample showed that the optical effect can be recreated with modern materials and methods, but it did not establish the Romans' exact recipe.
The project, Molecular Photonic Breadboards, is funded by the EPSRC and run with the Universities of Sheffield and Bristol. It commissioned glass artist Elliot Walker, winner of season two of Netflix's Blown Away, to make a sculpture from the recipe. The piece combines the Lycurgus story with the Farnese Atlas, with the globe replaced by a cup.
The sculpture is scheduled to be unveiled at the Millennium Gallery during the Festival of the Mind, November 6 to 15, 2026, and will then become a permanent exhibit at the Turner Museum of Glass. The glass is expected to have mainly decorative uses. According to the material, the knowledge gained could contribute to new photonic materials and to advanced glasses for managing radioactive waste, a field studied by Professor Russell Hand's group at the university.
