A rare sapphire and diamond ring

A rare 15.53 carats Burma 'Royal Blue' oval-shaped sapphire and diamond ringEstimate 4,800,000 – HK$6,500,000 ($600,000-800,000). Photo Christie's Image Ltd 2015

Set with an oval-shaped sapphire weighing approximately 15.53 carats, flanked by bullet-cut diamonds, mounted in platinum, ring size 5¾

Accompanied by premium report no. 79045 dated 10 March 2015 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 remarkable size and weight combined with an attractive and saturated blue colour and an excellent purity. Microscopic examination and the analysed properties are consistent with those found in sapphires from the classical mines in Burma (Myanmar). Its saturated blue colour, poetically also referred to as 'royal blue', is due to a combination of well-balanced trace elements in the gemstone, typical and characteristics for the finest sapphires of Mogok, Burma. This sapphire has been spared exposure to heat treatment and its clarity and colour are thus entirely natural. A natural sapphire from Burma of this size and quality is rare and exceptional

Also accompanied by report no. 0603623 dated 15 March 2006 from the Gübelin Gemmological Laboratory stating that the 15.53 carat sapphire is of Burma (Myanmar) origin, with no indications of heating

Also accompanied by report no. GRS2005-060548 dated 1 June 2005 from the Gem Research Swiss Lab stating that the 15.53 carat sapphire is of Burma (Myanmar) origin, vivid blue (GRS type "royal blue"), with no indication of thermal treatment

Please note that two certificates are more than 5 years old and might require an update

Christie's. HONG KONG MAGNIFICENT JEWELS, 2 June 2015, Hong Kong