IMPORTANT TIFFANY & CO. DIAMOND & SAPPHIRE RING Rectangular cushion cut blue sapphire, approx. 4.50 cts. (9.68mm x 8.83mm x 6.47mm), framed by a line of circular cut diamonds, to shoulders of graduated calibre cut diamonds, approx. 1 ct. TW. 51.1 gs. Size 6 1/2."