40004630, Marlborough, 326, Frontal head of Medusa., Market, Boardman, J., Scarisbrick, D., Wagner C., Zwierlein-Diehl, E: The Marlborough Gems (2009), Story-Maskelyne, M.H.: The Marlborough Gems (1870), Christies NY 29 April 2019, lot 35, Cameo, Onyx