A superb sapphire and diamond ring. Photo Christie's Image Ltd 2014

Set with a cushion-shaped sapphire weighing approximately 16.45 carats, flanked by rectangular and baguette-cut diamonds, mounted in platinum and 18k white gold, ring size 5¼. Estimate HK$4,800,000 – HK$6,500,000 ($621,805 - $842,028). Unsold

Accompanied by report no. 73385 dated 11 March 2014 from the SSEF Swiss Gemmological Institute stating that the approximately 16.00 carat sapphire is of Burma (Myanmar) origin, with no indications of heating and the colour of this sapphire may also be called 'royal blue' in the trade; also accompanied by an appendix stating that the sapphire possesses extraordinary characteristics and merits special mention and appreciation. The sapphire exhibits a beautifully saturated blue colour, combined with a fine purity and an attractive cutting style. Microscopic examination are consistent with those found in sapphires from the classical mines in Burma (Myanmar). Its saturated blue colour, poetically also described as "royal blue" in the trade, is due to a combination of well-balanced trace elements in the gemstone, typical and characteristic for the finest sapphires of Mogok, Burma. This sapphire has been spared exposure to heat treatment and its clarity and colour are thus all natural. A natural sapphire from Burma of this size and quality is rare and exceptional

Also accompanied by report no. 13075317 dated 29 July 2013 from the Gübelin Gemmological Laboratory stating that the 16.45 carat sapphire is of Burma (Myanmar) origin, with no indications of heating and this colour variety may also be called "royal blue" in the trade

Christie's. HONG KONG MAGNIFICENT JEWELS, 27 May 2014, Convention Hallhttp://www.christies.com/