Roman Coin Authentication Case Study

This case study presents a multi-technique, fully non-destructive characterization of two Roman coins from the reign of Julian II (361–363 CE): a gold solidus and a silver siliqua. Micro-computed tomography (micro-CT) was used to evaluate internal structure, revealing dense, crack-free material in both coins, with minor inclusions in the gold and slight voiding in the silver. High-resolution optical microscopy and patterned-light optical profilometry identified surface flow lines consistent with struck coinage, rather than casting. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) further confirmed elemental composition and revealed microscopic platinum-group inclusions (osmium/iridium) in the gold coin—features consistent with ancient refining methods. The silver coin exhibited expected sulfur- and oxygen-rich surface chemistry associated with natural aging and tarnish. Across all techniques, no evidence of modern manufacturing or casting was observed, supporting authenticity and traditional minting processes.