A one-cent postage stamp belonging to the late eccentric heir and famous murderer John du Pont has become the world's most valuable stamp - again. The 1856 British Guiana One-Cent Magenta sold on Tuesday at auction in New York for $9.5 million - although the stamp expected to bring between $10 million and $20 million. Still, the sale became the fourth time the stamp has broken the auction record for a single stamp in its long history. Sotheby's said the buyer wished to remain anonymous. The price included the buyer's premium. Scroll down for video . The one-cent 1856 British Guiana stamp is shown sold for $9.5 million on Tuesday at Sotheby's in New York . David Redden (L), Sotheby's Vice Chairman, and employees after the British Guiana One-Cent Magenta (R, on video screen), described as the most famous stamp in the world, sold for $9.5 million . Pictured here is the front (left) and reverse (right) side of the rare one-cent magenta coin . 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-1 1/4 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. 'You're not going to find anything rarer than this,' according to Allen Kane, director of the Smithsonian National Postal Museum. 'It's a stamp the world of collectors has been dying to see for a long time.' An 1855 Swedish stamp, which sold for $2.3 million in 1996, previously held the auction record for a single stamp. Owner: John E. du Pont, pictured in 1992, bought the stamp in 1980 and it was sold off after his death . Killed: Du Pont, left, was found to be mentally . ill when he shot dead Olympic wrestler David Schultz, left and right, at . his estate. The wrestler had been training the Olympic team at the time . of the killing in 1996 . Scene: Du Pont locked himself inside his mansion in Newtown Square, Pennsylvania for two days until police switched off his power and caught him when he went outside to fix a heater . 1856 The . stamp went into circulation after a . shipment of stamps was delayed from London. Printers in British Guiana . produced three stamps - including the one cent - to serve in their place . until the shipment arrived. 1873 Louis . Vernon Vaughan, 12, discovered the stamp in letter left by his uncle. The boy sells it to a local collector for six shillings, about $1.44 . today. 1878 McKinnon . sold it to a Liverpool dealer who . recognized it as uncommon. He paid 120 pounds . for it and resold it for 150 pounds to Count Philippe la . Renotiere von Ferrary, one of the world's greatest stamp collectors. 1917 . The count bequeathed his stamp collection to the Postmuseum in Berlin - . but it was later seized by France as war reparations and sold off . in a series of 14 auctions with the One-Cent Magenta bringing $35,000 in . 1922. 1940 Its . buyer, Arthur . Hind, a textile magnate from Utica, New York, died in 1933 and in 1940, . it was sold privately by his widow to Frederick Small for $45,000 . 1970 The stamp was put up for auction and it was purchased by an investment consortium for $280,000. 1980 J.E. du Pont bought the stamp for $935,000. June 17, 2014 The stamp will be auctioned by Sotheby's in New York, where it is expected to fetch as much as $20 million . David Beech, longtime curator of stamps at the British Library who retired last year, has compared it to buying the 'Mona Lisa' of the world's most prized stamps. The last owner was John E. du Pont, an heir to the du Pont chemical fortune who was convicted of fatally shooting 1984 Olympic champion wrestler David Schultz at his Pennsylvania estate in 1996. The stamp was sold by his estate, which will designate part of the proceeds to the Eurasian Pacific Wildlife Conservation Foundation that du Pont championed. Printed in black on magenta paper, it bears the image of a three-masted ship and the colony's motto, in Latin: 'we give and expect in return.' It went into circulation after a shipment of stamps was delayed from London and the postmaster asked printers for the Royal Gazette newspaper in Georgetown in British Guiana to produce three stamps until the shipment arrived: a 1-cent magenta, a 4-cent magenta and a 4-cent blue. While multiple examples of the 4-cent stamps have survived, only the tiny 1-cent issue is known to exist today. Its first owner was a 12-year-old Scottish boy living in South America who added it to his collection after finding it among family papers in 1873. He soon sold it for a few shillings to a local collector, Neil McKinnon. McKinnon kept it for five years before selling it to a Liverpool dealer who recognized the unassuming stamp as highly uncommon. He paid 120 pounds for it and quickly resold it for 150 pounds to Count Philippe la Renotiere von Ferrary, one of the world's greatest stamp collectors. Upon his . death in 1917, the count bequeathed his stamp collection to the . Postmuseum in Berlin. The collection was later seized by France as war . reparations and sold off in a series of 14 auctions with the One-Cent . Magenta bringing $35,000 in 1922 - an auction record for a single stamp. A Sotheby's empoyee (L) talks on the phone to the winning bidder as the British Guiana One-Cent Magenta, described as the most famous stamp in the world, sold for $9.5 million . David Redden (R), Sotheby's Vice Chairman, removes the British Guiana One-Cent Magenta (L) from its case after it sold for $9.5 million (with buyers' premium) at Sotheby's . David Redden, Sotheby's Vice Chairman, holds the British Guiana One-Cent Magenta after it sold for $9.5 million on Tuesday . Arthur . Hind, a textile magnate from Utica, New York, was the buyer. King . George V was an under-bidder. It is the one major piece absent from the . Royal Family's heirloom collection, Beech said. After Hind's death in 1933, the stamp was to be auctioned with the rest of his collection until his wife brought a lawsuit, claiming it was left to her. The next owner was Frederick Small, an Australian engineer living in Florida who purchased it privately from Hind's widow for $45,000 in 1940. Thirty years later, he consigned the stamp to a New York auction where it was purchased by an investment consortium for $280,000 - another record.The stamp set its third record in 1980 when it sold for $935,000 to du Pont.
The 1856 British Guiana One-Cent Magenta sold on Tuesday for $9.5 million - although it was predicted to sell for as much as $20 million .
It was the fourth time the stamp has broken the auction record for a single stamp in its long history .
The stamp was found by a 12-year-old boy and went through numerous stamp collectors' hands until it was bought by John du Pont in 1980 .
Du Pont shot dead Olympic wrestler David Schultz on his property in 1996 and passed away in prison in 2010 .
Sotheby's said the buyer wished to remain anonymous .
A one-cent postage stamp belonging to the late eccentric heir and famous murderer John du Pont has become the world's most valuable stamp - again. The 1856 British Guiana One-Cent Magenta sold on Tuesday at auction in New York for $9.5 million - although the stamp expected to bring between $10 million and $20 million. Still, the sale became the fourth time the stamp has broken the auction record for a single stamp in its long history. Sotheby's said the buyer wished to remain anonymous. The price included the buyer's premium. Scroll down for video . The one-cent 1856 British Guiana stamp is shown sold for $9.5 million on Tuesday at Sotheby's in New York . David Redden (L), Sotheby's Vice Chairman, and employees after the British Guiana One-Cent Magenta (R, on video screen), described as the most famous stamp in the world, sold for $9.5 million . Pictured here is the front (left) and reverse (right) side of the rare one-cent magenta coin . 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-1 1/4 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. 'You're not going to find anything rarer than this,' according to Allen Kane, director of the Smithsonian National Postal Museum. 'It's a stamp the world of collectors has been dying to see for a long time.' An 1855 Swedish stamp, which sold for $2.3 million in 1996, previously held the auction record for a single stamp. Owner: John E. du Pont, pictured in 1992, bought the stamp in 1980 and it was sold off after his death . Killed: Du Pont, left, was found to be mentally . ill when he shot dead Olympic wrestler David Schultz, left and right, at . his estate. The wrestler had been training the Olympic team at the time . of the killing in 1996 . Scene: Du Pont locked himself inside his mansion in Newtown Square, Pennsylvania for two days until police switched off his power and caught him when he went outside to fix a heater . 1856 The . stamp went into circulation after a . shipment of stamps was delayed from London. Printers in British Guiana . produced three stamps - including the one cent - to serve in their place . until the shipment arrived. 1873 Louis . Vernon Vaughan, 12, discovered the stamp in letter left by his uncle. The boy sells it to a local collector for six shillings, about $1.44 . today. 1878 McKinnon . sold it to a Liverpool dealer who . recognized it as uncommon. He paid 120 pounds . for it and resold it for 150 pounds to Count Philippe la . Renotiere von Ferrary, one of the world's greatest stamp collectors. 1917 . The count bequeathed his stamp collection to the Postmuseum in Berlin - . but it was later seized by France as war reparations and sold off . in a series of 14 auctions with the One-Cent Magenta bringing $35,000 in . 1922. 1940 Its . buyer, Arthur . Hind, a textile magnate from Utica, New York, died in 1933 and in 1940, . it was sold privately by his widow to Frederick Small for $45,000 . 1970 The stamp was put up for auction and it was purchased by an investment consortium for $280,000. 1980 J.E. du Pont bought the stamp for $935,000. June 17, 2014 The stamp will be auctioned by Sotheby's in New York, where it is expected to fetch as much as $20 million . David Beech, longtime curator of stamps at the British Library who retired last year, has compared it to buying the 'Mona Lisa' of the world's most prized stamps. The last owner was John E. du Pont, an heir to the du Pont chemical fortune who was convicted of fatally shooting 1984 Olympic champion wrestler David Schultz at his Pennsylvania estate in 1996. The stamp was sold by his estate, which will designate part of the proceeds to the Eurasian Pacific Wildlife Conservation Foundation that du Pont championed. Printed in black on magenta paper, it bears the image of a three-masted ship and the colony's motto, in Latin: 'we give and expect in return.' It went into circulation after a shipment of stamps was delayed from London and the postmaster asked printers for the Royal Gazette newspaper in Georgetown in British Guiana to produce three stamps until the shipment arrived: a 1-cent magenta, a 4-cent magenta and a 4-cent blue. While multiple examples of the 4-cent stamps have survived, only the tiny 1-cent issue is known to exist today. Its first owner was a 12-year-old Scottish boy living in South America who added it to his collection after finding it among family papers in 1873. He soon sold it for a few shillings to a local collector, Neil McKinnon. McKinnon kept it for five years before selling it to a Liverpool dealer who recognized the unassuming stamp as highly uncommon. He paid 120 pounds for it and quickly resold it for 150 pounds to Count Philippe la Renotiere von Ferrary, one of the world's greatest stamp collectors. Upon his . death in 1917, the count bequeathed his stamp collection to the . Postmuseum in Berlin. The collection was later seized by France as war . reparations and sold off in a series of 14 auctions with the One-Cent . Magenta bringing $35,000 in 1922 - an auction record for a single stamp. A Sotheby's empoyee (L) talks on the phone to the winning bidder as the British Guiana One-Cent Magenta, described as the most famous stamp in the world, sold for $9.5 million . David Redden (R), Sotheby's Vice Chairman, removes the British Guiana One-Cent Magenta (L) from its case after it sold for $9.5 million (with buyers' premium) at Sotheby's . David Redden, Sotheby's Vice Chairman, holds the British Guiana One-Cent Magenta after it sold for $9.5 million on Tuesday . Arthur . Hind, a textile magnate from Utica, New York, was the buyer. King . George V was an under-bidder. It is the one major piece absent from the . Royal Family's heirloom collection, Beech said. After Hind's death in 1933, the stamp was to be auctioned with the rest of his collection until his wife brought a lawsuit, claiming it was left to her. The next owner was Frederick Small, an Australian engineer living in Florida who purchased it privately from Hind's widow for $45,000 in 1940. Thirty years later, he consigned the stamp to a New York auction where it was purchased by an investment consortium for $280,000 - another record.The stamp set its third record in 1980 when it sold for $935,000 to du Pont.
eccentric heir and famous murderer John du Pont again. The 1856 British Guiana One-Cent Magenta million - although the stamp expected to bring sale became the fourth time the stamp has broken the auction record for a single stamp in its long history. Sotheby's said the buyer wished to 1992, bought the stamp in 1980 and it was sold Olympic wrestler David Schultz, left and right, expected to fetch as much as $20 million . David Pennsylvania estate in 1996. The stamp was sold $9.5 million on Tuesday . Arthur . Hind, a