Composite gems in medieval era: the art of counterfeiting before the sixteenth centuryS. Martiniello, S. Legnaioli, I. Bertelli, E. Ribechini and S. RaneriEur. Phys. J. Plus, 140 6 (2025) 571DOI: https://doi.org/10.1140/epjp/s13360-025-06505-8