A 2,000-year-old coin - one of only 22 made - has sold at auction for £400,000.
The gold coin, known as an aureus, shows the emperor Augustus in the form of Apollo on one side and an image of a heifer on the other. It's the most desirable of five different versions of the coin and is entirely unique.
"This is a truly extraordinary coin," says Christopher Webb, head of the coins department at auctioneer Dix Noonan Webb.
"Not only is it a unique type of an already very rare coin, but its condition after more than 2,000 years is extremely fine and visually it is a beautiful work of art. It also represents an epic period when Augustus built an empire that changed the course of human history."
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It's not known exactly when the coin was struck - although it's likely to be shortly after Augustus founded the Principate, the first phase of the Roman Empire, in 27BC.
He reformed the taxation system, developed a network of roads, established a standing army and constructed new buildings in Rome.
The reason for the high price is the extreme rarity of the coin. Only 21 other examples are known to exist, of which 15 are in museums, leaving just seven for collectors to compete for. This one went for well over the £300,000 estimate: indeed, once fees are included, the buyer will have paid £480,000.
It's not known whether the successful buyer was looking for a work of art - or for a good investment. But the coin could certainly be the latter. According to the Knight Frank Luxury Investment Index, rare coins have gained in value by 225% over the last ten years, 9% in the last year alone. It makes them one of the best-performing collectibles investments, second only to cars.
Specialist investment firm Blanchard advises would-be collectors to choose quality over quantity, and target rare coins, particularly those whose rarity isn't reflected in the price or which are required to fill a set. And don't expect a quick return: "Buy the rarest, highest-grade coins you can afford, and hold them for the long term," they say.
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