The shape of this box, known as a boite à ballon, is unusual in this material. Such boxes were more often executed in tortoiseshell and not, in this case, agate. The lid is set with a cameo of Diana and the body is cut with a profile of Hercules. Diana was the Roman goddess of the hunt, wild animals and woodland, also associated with the moon. Hercules was a hero in Greek and Roman mythology whose legend included twelve feats of strength and endurance known as 'the twelve labours of Hercules'.

Sir Arthur Gilbert and his wife Rosalinde formed one of the world’s great decorative art collections, including silver, mosaics, enamelled portrait miniatures and gold boxes. Arthur Gilbert donated his extraordinary collection to Britain in 1996.