▋For modern coins in general circulation the most common method of protection from forgeries is the use of bi-metallic coins, made of two metals of different color, which are difficult to counterfeit at low cost.
When the euro was introduced into Europe there were initially very few counterfeits, however the number increased massively as time went by. The high and increasing number of fake euro coins in circulation led to the creation of a Technical and Scientific Center for the coordination of technical actions to protect euro coins against counterfeiting.
It was estimated that 3.04% of all UK £1 coins in circulation are counterfeit. Between 2002 and 2006, approximately 400,000 counterfeit euro coins were removed from circulation, however “the overall number is very small by historical standards and by comparison to the 69 billion circulating (genuine) euro coins”