The world's 'most expensive' coin about to go on sale - £16m and covered in diamonds

The world's "most valuable" coin, covered in more than 6,000 diamonds, is about to go on sale. The Crown Coin: Her Masterpiece, commemorating the late Queen Elizabeth II, was last independently valued at £16million in 2022, and it is set to go to auction on September 25.

The starting bid estimate is £2-3 million, although experts have suggested the coin's rarity could see it achieve more, according to auctioneers Stanley Gibbons Baldwin's. The collection piece features 3.61kg of gold and is encrusted with a staggering 6,426 diamonds, weighing 483.57 carats in total.

A 1kg gold coin sits in the centre of the collection piece, which is encirled by ten 24-karat gold coins, four of which bear official portraits of Queen Elizabeth II.

Six coins represent the virtues truth, justice, charity, courage, victory, and constancy, which are also seen on the Victoria Memorial outside Buckingham Palace.

On the opposite face, a portrait of the late Queen Elizabeth II sits in the centre, surrounded by diamonds in the shape of the Union Jack flag.

Minted by the East India Company, it bears eleven legal tender 999.9 gold coins and measures 23.5cm wide by 3cm deep.

More than 83 artists from eight countries contributed to its creation. The diamonds were cut and polished in Australia, South Africa, and Canada, then certified by the Gemological Institute of America (GIA).

The design was conceived in Britain, refined in Sri Lanka and England, engraved in Singapore, coins minted in Germany and the Netherlands, and finally assembled in India.

"This is more than a coin; it is a cultural artefact," said a spokesperson from Stanley Gibbons Baldwin's, who believed it "stands alongside the most celebrated creations in numismatic history".

"It is a once-in-history tribute to a sovereign whose reign will never be equalled," they added.

The auction will be open to bidders worldwide, both live in person at Stanley Gibbons Baldwin's flagship at 399 Strand, London, and through its digital platform.