Most expensive ruby per carat sold at auction

The 25.59-carat "Sunrise Ruby", set with diamonds in a ring made by Cartier, sold for 28,250,000 Swiss francs ($30,274,100; £19,552,200; €27,122,000), including commission, to an anonymous buyer at Sotheby's auction house in Geneva, Switzerland, on 12 May 2015. This puts its per-carat price at an incredible 1,103,946 Swiss francs ($1,183,044; £764,009; €1,059,770).

The Sunrise Ruby originates from Myanmar. It is described as a "pigeon's-blood ruby" – the rarest and most precious class of rubies, distinguished by its intense colour.

Its original auction estimate was between $12 million and $18 million. Its total sale price is also a record for a single ruby.