Colombian Emerald and diamond ring, Tiffany & Co., early 20th century. Estimation 20,000 — 30,000 GBP. Photo Sotheby's.

Claw-set with a cabochon emerald between circular-cut diamond shoulders, N1/2, signed Tiffany & Co.

Accompanied by the Gem & Pearl Laboratory report no. 10719, stating that the emerald is Colombian, with evidence of minor clarity enhancement. 

Sotheby's. Fine Jewels, Londres, 18 mars 2015, 10:30 AM