On October 26, 2026, the University of Sheffield reported that researchers had developed a repeatable glass recipe informed by a fragment of the Lycurgus Cup. The glass recreates the Roman cup’s signature effect: green in reflected light and red when light passes through it. Sheffield’s announcement describes production of the effect in quantity, while the sculpture made with the glass is scheduled to debut in Sheffield in November.
Sheffield’s recipe followed an earlier glass sample
The 2026 announcement describes a later stage of work than the one reported in a 2025 paper by Lisa Hollands, Caroline Jackson and John Parker. The paper says the researchers produced an initial glass with a similar optical effect after four months of initial work, then continued with melt trials and characterization. Sheffield’s 2026 announcement reports a repeatable recipe based on a fragment of the original glass.
Hollands and Jackson developed a base glass using modern materials intended to mimic Roman starting materials. Hollands tested different furnaces, starting materials and oxygen levels, and also tried sugar. The reported recipe aims to reproduce the effect; Sheffield says the exact method used by Roman glassmakers remains unknown.
Why the cup looks green in one light and red in another
The Lycurgus Cup is a Roman glass cage cup dating to around the fourth century CE. A 2007 study reported silver-gold alloy nanoparticles in its glass, typically about 70 nanometers across, and linked them to the color effect. The university describes the recreated glass as jade green in reflected light and ruby red in transmitted light. “Dichroic” describes this difference in color depending on how light interacts with the material.
Other demonstrations use different materials. A separate 2020 Dutch research effort produced a similar effect in a 3D-printable nanocomposite. A 2020 paper also described related color effects using gold and silver nanoparticle solutions. Those demonstrations are distinct from Sheffield’s glass recipe.
Elliot Walker’s sculpture is scheduled for a Sheffield debut
The University of Sheffield commissioned glass artist Elliot Walker to make a contemporary sculpture using Hollands’ recipe. Walker drew on the Lycurgus story and the Farnese Atlas sculpture, replacing the Atlas’s globe with a cup. Sheffield announced that the work was scheduled to debut at the Millennium Gallery during the Festival of the Mind, November 6 to 15, 2026, before a planned permanent display at the Turner Museum of Glass.
Sheffield says the glass is mainly decorative, while the research may inform photonic materials and advanced glass for radioactive-waste management.
