“The Story of the World’s Rarest and Most Famous Stamp” was the title of the catalogue note when the British Guiana One-Cent Black on Magenta was scheduled to be sold at auction by Sotheby’s New York on June 17, 2014. (The picture above is an edited version of a picture from Wikimedia Commons.) From the Sotheby’s page:
For the fourth time in its illustrious history, the British Guiana One-Cent Black on Magenta set a new world auction record for any stamp yesterday at Sotheby’s New York, achieving $9,480,000 – nearly 1 billion times its original face value. No stamp is rarer than the sole-surviving example of the British Guiana, a unique yet unassuming penny issue from 1856, which has been heralded as the pinnacle of stamp collecting for more than a century.