Platinum, sapphire and diamond 'Trombino' ring, Bulgari. Photo courtesy Sotheby's

Centered by an oval-shaped sapphire weighing 28.09 carats, the mounting set with round and baguette diamonds weighing approximately 8.35 carats, size 8½, fitted with inner sizing band, signed Bulgari. Estimate:  $400,000 – $600,000

Accompanied by AGL report no. CS 55223 stating that the sapphire is of Classic Burmese origin, with no indications of heating. The report also states that, “The unusual combination of size, provenance, absence of treatment and quality factors present in this material contributes favorably to its rarity and desirability.”

For a ring of similar design, see Bulgari: 125 Years of Magnificence, by Amanda Triossi, pages 278 and 279.

Sotheby's. Magnificent Jewels. New York | 11 Dec 2013 - www.sothebys.com