40005024, Marlborough, 561, Portrait (frontal): Caracalla (?). Frontal bust of Caracalla. Signed PICHLER EPOIEI., PICLER EPOIEI, Museum of Fine Arts, Boston, Boardman, J., Scarisbrick, D., Wagner C., Zwierlein-Diehl, E: The Marlborough Gems (2009), Story-Maskelyne, M.H.: The Marlborough Gems (1870), 99.115, Cameo, Sardonyx