A rare One-Cent Magenta postage stamp printed in British Guiana in 1856, and most recently owned by the estate of a DuPont chemical company heir convicted of murder, is expected to fetch a record price of $10-$20 million, Sotheby's said on Monday.
The stamp is being sold by the estate of the late John du Pont, who died aged 72 in a Pennsylvania prison in 2010 where he was serving a sentence for the 1996 shooting of Olympic champion U.S. wrestler David Schultz.
Du Pont, whose wealth was estimated at $250 million at the time of his 1997 trial, was one of the richest murder defendants in U.S. history at the time of his conviction.
Sotheby's said experts from the Royal Philatelic Society London had re-authenticated the British Guiana One-Cent Magenta, the only one of its kind known to exist, and the auctioneer would offer the stamp at auction in New York on June 17.
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"It is one inch by one and a quarter inches, it's tiny and when it sells it will be the most valuable object by weight and size ever sold," David Redden, Sotheby's vice chairman and director of special projects, told Reuters.