NEW YORK - A 1-cent postage stamp from a 19th century British colony in South America has become the world's most valuable stamp -- again.
Sotheby's says the 1856 British Guiana One-Cent Magenta sold Tuesday at auction in New York for $9.5 million.
It's the fourth time it has broken the auction record for a single stamp in its long history.
The stamp was expected to bring between $10 million and $20 million. Sotheby's says the buyer wished to remain anonymous.
Measuring 1 inch-by-1 1/4 inches, the One-Cent Magenta hasn't been on public view since 1986. It's the only major stamp absent from the British Royal Family's private Royal Philatelic Collection.
An 1855 Swedish stamp previously held the auction record for a single stamp. It sold for $2.3 million in 1996.