A PUB punter bought a pint in his local - and got an "extremely valuable" £1 coin in his change.
Aaron Coulson has already been offered £100 for the coin after buying a beer in the Bottle of Sack pub in Sutton Coldfield.
The coin is supposed to be made with a gold outer ring and silver middle, but instead it's silver all over.
Even though the new 12-sided £1 coin is supposed to be one of the"most secure in the world" some of them, like Aaron's, have been minted with a mistake in the design.
Error coins that make it into circulation are very attractive to collectors, who may be willing to pay a huge sum for it.
And it's good news for coin hunters too because they're made in batches which means there could be hundreds more of the rare silver £1 coin out there - or it could be a one-off.
Aaron was totally unaware of the coin's value, but by fluke he was sat near a collector who offered him a wad of cash for it.
Gardener Aaron, 27, said: "I bought my pint and as the barman was giving me the change he noticed there was something different about one of the £1 coins.
"We looked at it and realised it was all silver - I'd never seen one like that before.
He added: "A man who was in the pub who claimed he was a coin collector offered me £50 for it.
Why is the £1 coin silver and how much is it worth?
THE Royal Mint manufactures four million coins a day, so you can see how sometimes things go wrong during the minting process.
But it's pretty rare if a batch of error coins makes it into circulation, which makes them very attractive to collectors.
It looks like Aaron's rare £1 coin was accidentally stamped on silver coloured nickle-plated alloy, rather than on two types of metal - nickel-brass and nickel-plated alloy.
It's likely to be down to a blank that didn't have the hole punched that slipped into the minting process by accident.
It's not yet clear how many have been minted this way which makes it even more valuable to a collector.
It can take up to a year for the Royal Mint to confirm how many of them have entered circulation.
Last year, a zinc coloured £2 error coin that was entirely made out of nickel brass was found in someone's change.
Approximately 10,270,000 of these types of coins were issued for circulation in 2007 and experts valued to be worth more than £1,300.
"I said no, but then he upped his offer and said he'd give me £100 and actually got out the cash.
"I figured that if he was prepared to pay £100 for it straight away, it must be worth more than that."
Find out why the 50p coins in your purse could be worth up to £840
The dad-of-one now plans to research the coin and find out its true value.
A coin expert at Chards told the it was "extremely valuable".
She said: "The pound coins which are all silver have been struck from the incorrect blank and are extremely rare.
"As to how much it's worth - that's entirely dependent on how much someone is prepared to pay for it.
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"If it is genuine, he should put it on eBay - saying it has been authenticated by the Royal Mint - and see how high the bidding goes."
Earlier this year a gran found a rare coin worth £100,000 in an old junk box she was about to throw out.
And we revealed how to see if your £2 coin are worth a mint.
Is your small change worth a fortune?
IF you think that you might have a rare coin then you might be able to make a real mint.
The most valuable coins are usually those with a low mintage or an error.
These are often deemed the most valuable by collectors.You should check how much the coin is selling for on eBay.
Search the full name of the coin, select the "sold" listing and then toggle the search to "highest value".
It will give you an idea of the amount of money that the coin is going for.
You can either choose to sell the coin on eBay or through a specialist like ChangeChecker.org.
If you choose the auction website then remember to set a minimum price that is higher or at the very least equal to the face value of the coin.
Even if your coin “sells” on eBay for a high price there’s no guarantee that the buyer will cough up.
It its terms and conditions, the auction website states that bidders enter a “legally binding contract to purchase an item”, but there’s no way to enforce this rule in reality.
The most eBay can do is add a note to their account for the unpaid item or remove their ability to bid and buy.
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