Instructions
Acquire an official pound sterling coin from a bank.
Examine the lettering around the rim of the coin you are testing and compare it to the official coin. Often, counterfeit coins will have lettering that is in the wrong font or is indistinct.
Examine the ribbing around the rim of the coin. Many counterfeiters have difficulty replicating the ribbing around the coin, resulting in an edge smoother than a real pound sterling coin.
Check for the imprints around the rib of the coin, as they are often omitted on counterfeit coins.
Check with the Royal Mint's website to ensure that the year on the coin corresponds with the design on the coin.
Hold the coin so that the image of the Queen is upright and flip the coin horizontally about its axis, being sure not to turn it clockwise or counterclockwise as you do so. Check that the image on the back of the coin is also oriented upright, as counterfeit coins will often improperly align the image on the front and the image on the back of the coin.