A Magnificent Pear-shaped Golconda Diamond Necklace. Photo: Christie's Images Ltd., 2010

The antique pear-shaped Golconda diamond, weighing 26.17 carats, suspended from a cushion-shaped diamond weighing 1.28 carat, to the briolette diamond chain and diamond-set barrel-shaped clasp, mounted in platinum, 47.0 cm - Estimate CHF3,000,000 - CHF5,000,000 ($3,084,670 - $5,141,116)

Accompanied by report no.5101776869 dated 8 June 2010 from the GIA Gemological Institute of America stating that the 26.17 carats diamond is D colour, Internally Flawless clarity, with a letter stating that it is a Type IIa diamond

Report no. 1005218 dated 31 May 2010 from the Gübelin GemLab stating that the 26.17 carats diamond is D colour, Internally Flawless clarity, with a Note stating it is a Type IIa diamond and an Appendix stating that 'Diamonds of this type, exhibiting an antique cutting style as well as a superior quality, are very rare and will most certainly evoke references to the historic term of Golconda'

Report no. 1122394117 dated 29 July 2010 from the GIA Gemological Institute of America stating that the 1.28 carat diamond is D colour, VS2 clarity

Christie's. Jewels: The Geneva Sale, 17 November 2010. Geneva www.christies.com