The art of engraving gemstones can be traced back to ancient Greece in the 8th century BC and earlier. Techniques passed down to the Egyptians and then to the Romans. There were major revivals of interest in engraved gems in Europe during the Byantine era, the Middle Ages, the Renaissance, and again in the 18th and 19th centuries. At each stage cameos and intaglios, these skillful carvings on a minute scale, were much prized and collected, sometimes as symbols of power mounted in jewelled settings, sometimes as small objects for private devotion or enjoyment. The subject of this intaglio, engraved in the early years of the Roman empire, has been identified as Neptune with one of his consorts, Amymone. In Greek mythology Neptune rescued the princess Amymone, one of the Danaid or daughters of King Danaus, from rape by a satyr. Neptune then fathered a son, Nauplius with her, and his descendants founded the port of Argos from which the Greeks sailed for the Trojan war.