It's a piece of paper just an inch square - but this nineteenth-century stamp from British Guiana has just sold at Sotheby's in New York for over $9 million at auction - the highest price ever paid for a stamp.
The stamp, which portrays a three-masted ship on a magenta background, along with the colony's motto, "We give and expect in return", is as rare as a stamp can get.
British Guiana was one of the first countries in the New World to start issuing stamps, just ten years after they were introduced in the UK in 1840.
"But in 1856, they ran out, and the postmaster had to ask the printer of the newspaper to print a contingency supply," says Selby Kiffer, vice president of Sotheby's, which auctioned the stamp.
"There were two denominations: the four-cent, which is very rare but does survive in multiple copies, and the one-cent: only one of these has ever been known since this example was first discovered in 1873."
The last owner was John du Pont, heir to the chemical firm, who was convicted in 1997 of murdering an Olympic champion wrestler. The stamp has been sold by his estate, following his death in prison in 2010, and the proceeds are to go to the Eurasian Pacific Wildlife Conservation Foundation.
But are stamps a good investment? Not according to Cambridge and London academics, who recently examined the returns on a number of different investments, from fine wines to government bonds and, yes, stamps.
Using a huge dataset of 36,000 prices between 1899 and 2012 from Christie's and Berry Bros, the team found a real financial return on investment of 5.2 percent fo equities, 4.1 per cent for fine wines, 2.4 per cent for art and 2.8 per cent for stamps.
Alternative investments such as stamps can also be risky - particularly for non-experts. They are unregulated, meaning that if things go wrong, there's no recourse to an ombudsman. But, says Kiffer, stamp-collecting is rarely just about the money - particularly in the case of the British Guiana.
"It's more than just the rarity - it's the romance," he says. "It was printed just 16 years after the first stamp was produced. People expected other examples to turn up, but they never have."