 Art deco emerald and diamond Ring by Tiffany &amp;amp; Co., New York, circa 1925, for Helen Hay Whitney.&amp;nbsp;Emerald-cut emerald in a millegrain bezel accented on the sides with old European-cut diamonds in millegrain settings, creating a four-leaf form. Mounted in platinum. 1 emerald, 8.51 carats; 34 diamonds, .50 carat. 