The term intaglio refers to a small image that has been engraved into a gemstone and usually set in a piece of jewellery, most commonly a ring. Such artistic form has its origin in Sumer in the 4th millennium BC, with the appearance of cylinder and stamp seals, whereby decorations and patterns were engraved into soft stones. During the Hellenistic period and the early Roman Empire, the art of intaglio reached its apogee, with there being a steady decline in craftsmanship in the late Imperial Rome, until a revival of interest with the Byzantine and during the Renaissance.
The subject used for intaglios are diverse, with depictions of deities being a favourite theme. In Greek and Roman mythology, ‘Dioscuri’ (Διόσκουροι) is the name used to identify the twin half-brothers Castor (Κάστωρ) and Pollux (Πολυδεύκης – Polydeuces), sons of Leda and Tyndareus, King of Sparta, and Zeus respectively. They were regarded as patrons of humankind and protectors of travellers and sailors. Consistently associated with horses in classical arts and literature, their typical iconography sees them portrayed as helmeted horsemen holding a spear.