Three kilos of gold, 6,462 diamonds and the size of a plate: Is this the world’s most valuable coin?

One of the world’s most valuable coins will go under the hammer at Stanley Gibbons Baldwin’s in London this month. Made out of 3.61kg of pure gold, the coin is studded with 6,462 diamonds and is roughly the size of a dinner plate. It was crafted across eight different countries by over 83 people for Elizabeth II’s Platinum Jubilee.

Although the one-of-a-kind piece was issued by the British Overseas Territory of Saint Helena as a £10,000 coin, it was independently valued at £16 million in 2022. It is surprising then that it will come to the market with a conservative starting estimate of £2-3 million.

Richard Gladdle, a numismatist who specialises in British coins at Stanley Gibbons Baldwin’s, said: ‘The problem is, we normally value things by precedent — by what a similar coin has fetched at auction three months ago — but with this there is no precedent. It’s very difficult to give it a market value without first having tested [whether it is] so. I suppose that’s why it’s coming to auction at that reserved price.’

Gladdle added: ‘When it comes to the denomination value [£10,000], really, they could have called it a £5 piece, but the actual value — because it's made of solid gold — is far more, but it sort of makes it a coin if you give it a value.’

‘You could actually go to a shop in Saint Helena and buy some baked beans and groceries with this coin, and even get a little change back [...] but it's also a work of art, and the value of the work of art is far more than the denominational value.’

The piece itself is international, just as Elizabeth II’s reign was. The diamonds were cut and polished in Australia, South Africa, and Canada, then certified by the Gemological Institute of America. The design was conceived in Britain, refined in Sri Lanka and England, and engraved in Singapore. The coins were minted in Germany and the Netherlands, and finally the piece as a whole was assembled in India.

It is also a complete oddity. Gladdle said: ‘Normally if you make a coin for a country you don't make one, you make a few, even if it’s just a commemorative piece that’s going to be handed out to VIPs, but I don’t know of any other example where there’s been just one coin made.’

Another interesting element of the sale is that the auction house will be accepting cryptocurrency. Aaron Carter, Stanley Gibbons Baldwin’s marketing director, explained: ‘It’s slightly unusual for an item like this, but provided people go through the right due diligence then, we will be able to accept this.’ The idea behind this is that the sale will be opened up to a wider audience. The auction, The Crown Coin: Her Masterpiece, will take place on September 25.

The coin itself is a decadent and intricate tribute to Britain’s longest reigning monarch, minted by The East India Company. Measuring 235mm in diameter and 30mm in depth, it weighs 483.57 carats in total. Out of the total 11 smaller coins embedded into the piece, five of them are official effigies of the Queen, the largest one of which weighs 1kg. Out of the 10 smaller coins around the edge, four of them feature the tiara Elizabeth II wore during her reign. The remaining six depict the six virtues: Truth, Justice, Charity, Courage, Victory and Constancy — inspired by the Queen Victoria Memorial which stands at the end of the mall in front of Buckingham Palace.

‘Not only is it a coin, but it's also a piece of art,’ Gladdle told me. Behind him and Carter hung a copy of an Andy Warhol portrait of Queen Elizabeth II. The Warhol series that contains this painting is one of the artist’s most valuable, Carter said. It is a visual reminder of the monarch’s persistent posthumous popularity.

So, with all the history, artistry and — frankly — bling wrapped up in this singular coin, the final question remaining is: who will buy it? ‘Obviously someone with a fairly strong bank account,’ said Gladdle.

The auction will be open to bidders globally, both live in person at Stanley Gibbons Baldwin’s flagship at 399 Strand, London WC2R 0LP and via its digital platform. For more details visit their website.