Lot 251. Platinum, 10.27 carats Type IIa Diamond and Sapphire Ring, France, circa 1920Estimate 400,000 — 600,000 USD. Photo: Sotheby's.

Centering an emerald-cut diamond weighing 10.27 carats, flanked by six baguette sapphires, size 6, with French assay and partial French workshop marks; circa 1920..

Accompanied by GIA report no. 2175733898 stating that the diamond is D color, VS1 clarity. Together with a letter from the GIA stating that the diamond has been determined to be Type lla.

Art Deco design is a powerful balance of bold form and restraint. Strong, at times soaring shapes—whether found in a Ruhlmann cabinet, a Georg Jensen cocktail shaker, or the Chrysler building—maintain a controlled linearity and limited color palette. The jewelers of the 1920s and ‘30s translated this aesthetic into the use of step-cut stones, including the now timeless emerald cut as well as the baguette cut, often applied to colored accent stones. 

The ring featured here is striking in its simplicity. Its elongated emerald-cut diamond is tightly flanked by vertically arranged sapphires guiding the eye in a sweeping direction. The whiter-than-white appearance of the diamond is attributable to a complete lack of nitrogen, placing the stone within the prized Type IIa category. Many of the world’s most famous diamonds are Type IIa—the Koh-i-Noor perhaps being the best-known example—and were discovered centuries ago in the legendary mines of Golconda.

Sotheby's. Magnificent Jewels Including the Legendary Stotesbury Emerald, New York, 25 Apr 2017, 10:00 AM