Black Jadeite and Diamond Ring, by Alessio Boschi . Photo courtesy Tiancheng International Auctioneer Limited

Centring on a rectangular black jadeite plaque, embellished by pavé-set diamond glacier motif, each end capped by a rose-cut black diamond surrounded with pavé-set diamonds. Mounted in 18 karat white gold. Black jadeite plaque measuring 30.74 x 11.33 x 5.09mm. Signed Alessio Boschi. Ring size: 6 3/4. Estimate US$10,500 - 13,000

Accompanied by Hong Kong Gems Laboratory report numbered GL77566 dated 18 March 2013, stating that the black jadeite is natural, known in the trade as "A jade".

Tiancheng International Auctioneer Limited. SPRING AUCTION 2013 JEWELLERY AND JADEITE. 15 Jun · 3 pm. Hong Kong Headquarters 30/F Bank of China Tower 1 Garden Road, Central Hong Kong http://www.tianchengauction.com/