Police say there are a number of ways to tell the coins are fake
Police have issued a warning about counterfeit pound coins which have been detected in a number of areas of NI, including north Down and Dundonald.
The counterfeit coins are missing the ring of dots normally found around the circumference of the coin.
However, they are similar in weight, colour and appearance to the legitimate coin.
A similar warning was issued to traders in the north west of Northern Ireland before Christmas.
Other clues in the general appearance of the counterfeit coins include the date and design on the reverse which should correspond.
The lettering or inscription on the edge of the coin should also correspond to the right year.
Although the coin may have been in circulation for some time the colouring may appear more gold and shiny and normal with little sign of ageing.