© Licensed to London News Pictures. 02/06/2014. LONDON, UK. An employee of Sotheby's auction house holds a case containing the sole-surviving 'British Guiana One-Cent Magenta' stamp dating from 1856, on June 2, 2014 in central London. The unique stamp is expected to fetch 10 to 20 million USD (£6-12m) when auctioned in New York, USA on June 17, 2014. The stamp was initially discovered in 1873 by a 12-year old Scottish boy living in British Guiana, South America who sold it to a local stamp collector for several shillings. Photo credit : Tolga Akmen/LNP