The Queen is holding the secret of the new £1 coin's "hidden" security feature, it can be revealed, as an invisible code which proves their authenticity is embedded in her face.
The Daily Telegraph understands that the top layer of metal on the surface of the coins contains pigments which form a secret binary code which is invisible to the naked eye.
The code can only be read when subjected to a specific frequency of ultraviolet light installed in the Royal Mint's special fake coin detection machines, sources close the the Royal Mint said.
Among other features the high-security code is behind the Royal Mint's claim that the 12-sided coin is the "most secure coin in the world", and has until now been shrouded in secrecy.
The binary code and the exact light frequency needed to see it remain a closely guarded secret known by the Government. Retailers, vending machines and members of the public are unable to detect the code at present.
It has also emerged that the Royal Mint has patented "electro-plating" technology relating to the application of luminescent particles on metal.
According to patent experts at Ashfords International Patenting Services the Royal Mint's technology ensures that the special particles don’t merely form a coating, but are actually part of the alloy of the material forming the new coin.
A spokesman said: "This makes the security feature durable, and able to withstand the high temperatures and pressures of the manufacturing process. This also means that the new £1 coin may glow under ultraviolet light (similar to the way some modern banknotes do) to indicate authenticity."
The new 12-sided £1 coin entered circulation on March 28, replacing the round pound, of which roughly one in 30 pound coins is a counterfeit - the equivalent of around £50m. To combat this, the new pound sports a number of security features.
The old coin will remain legal tender until 15 October this year, after which shops are under no obligation to accept it.
After that date, consumers will have to take the coin to a bank to exchange it.
A Treasury Spokesman said: “We have introduced a new pound coin, which is the most secure of its kind in the world, in order to clamp down on the multimillion-pound cost of counterfeits.
“This cutting-edge coin has a number of security features, including the visible hologram and the milled edges among other features. For obvious reasons, it would not be appropriate to be drawn on the security details.”
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