A marquise-shaped 18.88 carats diamond ring. Estimate CHF1,150,000 – CHF1,450,000 ($1,187,533 – $1,497,324). Photo Sotheby’s

Set with a marquise-shaped diamond, weighing approximately 18.88 carats, to the tapered baguette-cut diamond shoulders, mounted in gold, ring size 6½

Accompanied by report no. 2105639793 dated 26 June 2014 from the GIA Gemological Institute of America stating that the diamond is G colour, Internally Flawless clarity

Christie’s. GENEVA MAGNIFICENT JEWELS, 11 November 2014, Geneva