The Pink Star and other expensive diamonds – in pictures

A Christie's member of staff displays an unmounted, heart-shaped, D-colour, internally flawless, type IIa diamond weighing 56.15 carats. It fetched $10,953,661 in 2011 Photograph: Denis Balibouse/Reuters

A Christie's employee holds a 101.73-carat, pear-shaped diamond, the largest D-colour flawless diamond ever to be offered for sale at auction, which sold for $26.7m in May 2013 Photograph: Dominic Lipinski/PA

A model displays the Pink Star, a 59.60-carat, oval-cut pink diamond, at Sotheby's in Geneva. The diamond is the most expensive ever sold at auction, fetching $74,033,776 Photograph: Ruben Sprich/Reuters

A model poses with the Beau Sancy diamond during a Sotheby's auction preview in Geneva. The 35-carat pear-shaped diamond Marie de Medici wore at her coronation in 1610, one of the world's most famous gems, sold for £5m in 2012 Photograph: Fabrice Coffrini/AFP/Getty Images

A model poses with the Sun-Drop diamond during a press preview of a Sotheby's auction in Geneva. One of the world's largest diamonds, a pear-shaped, 110.3-carat yellow rock, it sold for just over $10.9m in 2011 Photograph: Fabrice Coffrini/AFP/Getty Images

A Christie's employee displays a rectangular-cut fancy vivid yellow diamond weighing 70.19 carats, in Geneva in 2012. The diamond was expected to fetch between $3.1m and $5m at auction Photograph: Martial Trezzini/Keystone/AP

A Sotheby's employee displays the largest brilliant-cut D-colour flawless diamond ever to appear at an auction. This diamond, weighing 84.37 carats, sold to the Guess clothing company founder Georges Marciano for just under $16.2m in 2007 Photograph: Fabrice Coffrini/AFP/Getty Images

A model holds the Archduke Joseph historical diamond during a Christie's auction preview in Geneva in 2012. Once part of the collection of the Archduke Joseph of Austria, the D-colour diamond, weighing 76,02 carats and mined at the Golkonda mine, sold for $21,474,525 (including commission) Photograph: Fabrice Coffrini/AFP/Getty Images

An employee holds a 34.05-carat, rectangular-cut diamond ring during an auction preview at Christie's in London in 2012. The ring fetched $5,117,253 Photograph: Stefan Wermuth/Reuters

A Sotheby's employee holds a 118.28-carat, D-colour, flawless, type 11A magnificent oval diamond, which sold for $30.6m at a Hong Kong auction on 7 October Photograph: Peter Foley/EPA

A 76.41-carat flawless diamond is pictured at Graff diamond jewellers in London. The diamond was cut from the 15th largest diamond in the world, called the Lesotho Promise. Photograph: Carl De Souza/AFP/Getty Images