Composite gems in medieval era: the art of counterfeiting before the sixteenth century S. Martiniello, S. Legnaioli, I. Bertelli, E. Ribechini and S. Raneri Eur. Phys. J. Plus, 140 6 (2025) 571 Published online: 23 June 2025 DOI: 10.1140/epjp/s13360-025-06505-8