Jean Schlumberger for Tiffany & Co., amethyst ring, c. 1974, oval amethyst triple bezel set in 18ct yellow gold, with brushed gold band, stamped 'Tiffany & Co., 18K P, Schlumberger', with box, approx. Weight 14.9 grams size S, cf. For comparison Tiffany & Co. 1974-75 blue book, p. 58