A COIN expert has revealed the exact words to spot on a rare £2 piece that's worth over £500.
Coins with minting errors can be worth multiple times their face value because there are so few of them.
The scarcity of the pieces means collectors are willing to pay hundreds or thousands of pounds for them.
And one TikTok user @thecoincollectoruk has revealed what words to look out for on one of the coins that's sold for over £500.
Explaining in a recent video, the user said: "If you find this £2 coin check it for an extremely rare error.
"This is the Lord Kitchener coin from 2014.
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"You can see that on the back of the at the bottom it says £2 on the correct version.
"The rare version does not say two pounds on the back."
There are just over 5,700,000 of these correct £2 coins in circulation.
But the TikTok user goes on to explain only two of the error coins have been discovered.
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They said: "One of these sold at auction for £500 and it's thought to be worth even more now."
It's worth digging around your spare change to see if you have one of the £2 coins and it's missing the crucial text.
How to check if a coin is rare
In most cases, a coin is rare if it has a low mintage figure - which is set by The Royal Mint.
The mintage figure relates to how many of the coins were made, so the fewer there are of them, the rarer they are.
You can find out what coins are rare and how they look on The Royal Mint's website.
Your next step after this is to see if the same coin is still available to buy in superior Brilliant Uncirculated quality from an official Royal Mint distributor, according to Change Checker.
These coins have been specially made to a superior quality which differentiates them from other coins you might find in your pocket.
It's not just a coin's mintage that dictates whether it's rare though.
Minting error pieces can sell for hundreds of times their face value too - because there are so few of them.
If you want to find out if your coin was made incorrectly, you can check out our list of rare coins here.
Meanwhile, you can use websites like changechecker.org which regularly posts about error coins.
How to sell a rare coin
If, after checking, you realise you've come across a rare coin, there are a number of ways you can sell it.
You can sell it on eBay, through Facebook, or in an auction.
But be wary of the risks.
For example, there are a number of scams targeting sellers on Facebook.
Crooks will say they're planning to buy the item, and ask for money upfront for a courier they'll be sending around.
But it's all a ruse to get you to send free cash to them - and they never have any intention of picking your item up.
It's always best to meet in person when buying or selling on Facebook Marketplace.
Ensure it's a public meeting spot that's in a well-lit area.
Avoid payment links and log in directly through the payment method's website.
Most sellers prefer to deal with cash directly when meeting to ensure it's legitimate.
The safest way to sell a rare coin is more than likely at auction. You can organise this with The Royal Mint's Collectors Service.
It has a team of experts who can help you authenticate and value your coin.
You can get in touch via email and a member of the valuation team will get back to you.
You will be charged for the service though - the cost varies depending on the size of your collection.
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Meanwhile, you can sell rare coins on eBay.
But take into account that if you manage to sell your item then eBay will charge you 10% of the money you made - this includes postage and packaging.