CIRCA MID 1ST CENTURY B.C.

This unusual material, ametrine, is a combination of purple amethyst and yellow citrine in a single gem. Engraved on this convex oval is Thetis, riding a hippocamp. She is nude but for a mantle around her legs. In her right hand she holds a circular shield, intended for Achilles, with a facing head of Medusa as the blazon. Below the sea-horse is the signature of the gem-engraver Aulos ("of Aulos"), which Sangiorgi did not consider original, but which Boardman and Wagner (op. cit., p. 190) thought possibly original. Aulos was a superb artist known from a number of signed gems; others have been assigned to him on account of similarity of style. Many gems engravers of the 18th and 19th century forged his signature on their own gems. During the Renaissance and later, his signature was added to unsigned ancient gems in order to increase their prestige and value. The stone is set into a gold finger ring, probably of the 19th century. For a Roman carnelian gem in Vienna with the same subject and date, excluding the Medusa blazon, see no. 408 in N. Icard-Gianolio and A.-V. Szabados, "Nereides," in LIMC, vol. VI.