40004612, Marlborough, 490, Bust of Athena (?), wearing a scale corselet; Corinthian helmet decorated with a snake., Unknown, Boardman, J., Scarisbrick, D., Wagner C., Zwierlein-Diehl, E: The Marlborough Gems (2009), Story-Maskelyne, M.H.: The Marlborough Gems (1870), no. 490, Cameo, Sardonyx