An important ruby and diamond ring. Photo Christie's Image Ltd 2014

Set with a cushion-shaped ruby weighing approximately 5.75 carats, within a surround set with oval-shaped diamonds alternating with brilliant-cut diamonds, mounted in 18k white and yellow gold, ring size 5½. Estimate HK$3,800,000 – HK$5,800,000 ($492,539 - $751,769)

Accompanied by report no. 73108 dated 11 March 2014 from the SSEF Swiss Gemmological Institute stating that the approximately 5.70 carat ruby is of Burma (Myanmar) origin, with no indications of heating; also accompanied by an appendix stating that the ruby possesses extraordinary characteristics and merits special mention and appreciation. The ruby exhibits an attractive vivid red colour combined with a fine purity. The small inclusions found by microscopic inspection represent the hallmarks of rubies from the classical ruby mines in the Mogok valley in Burma (Myanmar). Its vivid red colour is due to a combination of well-balanced trace elements in this gemstone, characteristic for the finest rubies from Mogok. The ruby has been spared exposure to heat treatment and its clarity and colour are thus all natural. A natural ruby from Burma of this size and quality is very rare and exceptional

Also accompanied by report no. 0508594 dated 25 August 2005 from the Gübelin Gemmological Laboratory stating that the 5.75 carat ruby is of Burma (Myanmar) origin, with no indications of heating

Also accompanied by report no. CS 37816 dated 15 June 2005 from the American Gemological Laboratories stating that based on available gemological information, it is the opinion of the Laboratory that the ruby weighing 5.75 carat is natural, the origin of this material would be classified as Classic Burma (Myanmar), heat enhancement: none, clarity enhancement: none

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

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