A rare One-Cent Magenta postage stamp printed in British Guiana in 1856 and most recently owned by the estate of a du Pont chemical company heir convicted of murder is expected to fetch a record price of between US$10 million (S$12.7 million) and $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 US wrestler David Schultz.
Du Pont, whose wealth was estimated at US$250million at the time of his 1997 trial, was one of the richest murder defendants in US 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.
"It is 1 inch by 1 and a quarter inches (2.54cm by 3.175cm), 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.
"Our estimate on this stamp is US$10million to US$20million. That seems like an awful lot, but in the great scheme of things, across the entire collecting world, the most extraordinary objects in every field, that price suddenly becomes a little modest."
Chris Harman, chairman of the Philatelic Society's expert committee, said the stamp printed in what is now called the Republic of Guyana was without peer.
"It's one of the first stamps in the world, 1856, British Guiana was one of the first countries in the world to issue their stamps, and this was a locally printed stamp, of which there are very few Four-Cent, and there's only one One-Cent, so it has gained this iconic status," he said.
It has not been on public view since 1986, when it was exhibited at a stamp show in Chicago. The last time it was certified as authentic by the Royal Philatelic Society was in 1935, when several attempts at forging it have been made.