With a thickness of 3.15mm, the coin was designed to be easy to make out from other loose change, although this has not stopped it from being targeted by counterfeiters - and almost three in every 100 pound coins are thought to be duds.
Ways to spot a fake include looking at how even the lettering is, seeing if the milled edge of the coin is even and well-defined and examining the colour. Genuine £1 coins which have been in circulation for some time appear more shiny and golden.
More information about how to spot a fake £1 coin is on the Royal Mint's website here.
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