Jean Schlumberger, Tiffany & Co. Carnelian ring, c. 1970, 18ct yellow gold, centring a cabochon carnelian, stamped 'Tiffany & Co. 750 Schlumberger Studios, weight approximately 20.8 grams size T. Provenance: cf. For comparison Tiffany & Co. blue book catalogue for 1971-1972, p. 39