Hidden Signatures in Roman Glass: How New Research Is Rewriting Ancient Craft History!
In 2023, a quiet moment in a museum gallery ended up reshaping what historians thought they knew about some of the Roman Empire’s most technically impressive glass vessels. Washington State University art historian and practising glassblower, Hallie Meredith, was examining a private collection of carved glass cage cups (or diatreta) at the Metropolitan Museum of Art when something unexpected caught her eye. On the back of one cup, a seemingly decorative motif appeared to repeat with suspicious consistency.
What many had dismissed as simple ornamentation suddenly looked far more intentional.
Diatreta were produced between the fourth and sixth centuries CE and are celebrated for their extraordinary craftsmanship. Each one begins as a thick lump of glass that is painstakingly carved into a delicate inner bowl surrounded by an openwork lattice, connected by impossibly fine bridges of glass.
Photo Credit: Corning Museum of Glass
Researchers have traditionally focused on these vessels’ inscriptions and astonishing technical skill. The smaller shapes often found near those inscriptions, diamonds, leaf-like forms, and cross-shaped figures, were largely ignored or written off as decorative flourishes.
Meredith’s close inspection suggests otherwise. Her findings, published in the Journal of Glass Studies and World Archaeology, point to these motifs being deliberate makers’ marks: visual signatures left by the workshops that produced them. By comparing nearly identical symbols across multiple surviving pieces, she argues that these vessels were the product of coordinated teams rather than isolated master craftsmen.
Meredith’s research goes beyond finished pieces. She studies tool marks, incomplete objects, and even repaired or recycled fragments to build a picture of a highly collaborative craft world. This was an environment in which engravers, polishers, and other specialists worked together and shared methods across different industries.
The symbols long referred to as “stop-marks” now appear to form a kind of visual shorthand, a coded language used within and between workshops to communicate during production.
This interpretation also challenges old debates about how diatreta were made. Instead of being produced using a single technique or relying purely on one artisan’s talent, these cups seem to have emerged from a collective process that could unfold over a long period. Their makers’ marks may even have acted like early branding, hinting that the idea of a workshop “logo” existed long before modern marketing.
As an experienced glassblower herself, Meredith brings a practical understanding of the physical skill and labour required. Her work emphasises the importance of viewing ancient craftsmen not simply through technical analysis, but as real people with training, creativity, and shared practices.
Her broader project also explores how craftworkers communicated through unconventional spellings, mixed alphabets, and unusual inscriptions. She is now collaborating with computer science students to develop a database that will track these features across thousands of objects, shedding light on how scribes and artisans operated in multilingual Roman communities.
All this evidence points to a Roman craft industry that was far more dynamic and interconnected than previously thought, one with its own systems of communication, collaboration, and identity. Thanks to a single, carefully observed detail in a museum gallery, the secret signatures of Rome’s master glassmakers are finally coming into view.