The genuine 2008 pound coin which has caused confusion
Some retailers in Northern Ireland are rejecting genuine pound coins as fakes, following a warning about an increase in counterfeit coins.
Police warned people to look out for fake coins which do not have a ring of dots normally found around the circumference of the coin.
However, some genuine 2008 and 2009 £1 coins do not have any dots.
A Royal Mint spokesman said fake coins may be darker in colour and the heads and tails could be non-symmetrical.
HOW TO SPOT A FAKE
Look at the edge - on fake coins lettering will often be indistinct, or the wrong typeface
Hold the coin so the Queen's head is upright and facing you. The pattern on the reverse side should also be upright
The colour can be a give-away, although real coins can become discoloured in circulation
Design on reverse should correspond with official design for year of its issue
Police sources say counterfeiting has become so sophisticated that it is nearly impossible for the untrained eye to tell.
Royal Mint spokesman Kevin Clancy said that while the ring of dots was "a real red-herring" when it comes to spotting a dud coin, there are a number of factors which can help in picking out the fakes.
He said the lettering might be more crude than on a genuine coin and it may show little sign of aging even after supposedly having been in circulation for several years.
"If you are given a £1 coin in your change, without even thinking you're instinctively assessing a range of factors - its weight, its diameter and colour," he said.
"The most obvious thing to look out for is the colour, as the weight is probably not going to be a deciding factor.
Joe McGivern of the West Belfast Traders' Forum said the confusion arose from shiny coins which were dated 2008.
"Counterfeit coins tend to be darker - look more closely at the lettering around the edge which will be more crudely rendered.
"On the portrait side and tail side, they tend to be more soft focus and crudely struck."
Another thing to look out for is the Queen's head being out of alignment with the reverse image, he said.
"If you hold the Queen's portrait upright and turn the coin around on the axis, the design on the tail side will be at an angle rather than upright," he said.
Alan Chambers, a North Down councillor who runs a supermarket in Groomsport told the BBC he believed the police and the banks had created panic around the issue of counterfeit coins.
He said the police warning about fake pound coins described them in such a way as to easily confuse them with the legitimate 2008 coins.
He said matters came to a head on Monday when a number of customers came into his shop saying other businesses in the area had refused to take pound coins they had received in his shop.
"I was able to reassure most people that the coins were legitimate.
"I think the police need to admit that they possibly got it wrong last week or at the very least clarify that these new shiny coins are legitimate."
Police believe there is no evidence to suggest a higher than usual number of counterfeit coins in circulation in Northern Ireland at the moment.