A diamond single-stone ring. Photo Christie's Image Ltd 2012

The rectangular cut-cornered diamond weighing approximately 18.47 carats, to baguette-cut diamond shoulders and a plain hoop. Estimate £160,000 - £180,000. Price Realized £277,250 ($446,095)

Accompanied by report no.2145851873 dated 17 July 2012 from The Gemological Institute of America (GIA), stating the 18.47ct diamond is J Colour, SI1 Clarity, faint fluorescence 

Christie's. Important Jewels. 12 December 2012. London, King Street