A 1-cent postage stamp from a 19th century British colony in South America has become the world’s most valuable stamp – again.

The 1856 British Guiana One-Cent Magenta sold Tuesday at auction in New York for $9.5 million, Sotheby’s said. It was the fourth time the stamp 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 said the buyer wished to remain anonymous. The price included the buyer’s premium.

David Redden, Sotheby’s vice chairman, called the sale “a truly great moment for the world of stamp collecting.”

“That price will be hard to beat, and likely won’t be exceeded unless the British Guiana comes up for sale again in the future,” Redden said.

Measuring 1 inch-by-1¼ inches, it hasn’t been on public view since 1986 and is the only major stamp absent from the British Royal Family’s private Royal Philatelic Collection.

Rare 1-cent stamp sells for $9.5 million