A sapphire and diamond necklace, by Harry Winston. Photo Christie's Image Ltd 2014.

The chevron-shaped brilliant-cut diamond necklace suspending at the front a detachable pendant/brooch centering upon an oval-shaped sapphire, weighing approximately 57.92 carats, within three rows of graduated brilliant-cut diamonds, mounted in platinum, pendant 4.2 cm.With maker's mark for Jacques Timey and signed Winston for Harry Winston. Estimate CHF1,100,000 – CHF1,800,000 ($1,251,287 - $2,047,561)

Accompanied by report no. 72711 dated 14 February 2014 from the SSEF Swiss Gemmological Institute stating that the sapphire is of Ceylon origin, with no indications of heating, and an Appendix for 'Exceptional Sapphire' indicating that the sapphire '.. exhibits a highly impressive size and weight of 57.924 ct, combined with a well-saturated blue colour and an attractive cutting style.' (2)

Christie's. GENEVA MAGNIFICENT JEWELS. 14 May 2014. Geneva - www.christies.com