Euro coins edge of the €2 coin also protects it from counterfeiting. Euro coins were designed in cooperation with organisations representing blind persons, and as a result they incorporate many features allowing them to be distinguished by touch alone. In addition, their visual appearance is designed to make them easy to tell apart for persons who cannot read the inscriptions on the coins. The coins increase in size and weight with value. Of the eight denominations of euro coins, the three lowest denominations are small, resemble copper in colour and are quite thin and light. The next three denominations resemble gold in
1 euro coin until 2007; and the famous Monegasque coin from 2007 without mint marks. 1 euro coin The 1-euro coin (€1) is a euro coin with a value of one euro (€1). It is made of two alloys: the inner part of cupronickel, the outer part of nickel brass. All coins have a common reverse side and country-specific national sides. The coin has been used since 2002, with the present common side design dating from 2007. As of July 2015, there were approximately 6.7 billion one-euro coins in circulation, constituting 26.4% of all circulated euro coins by value and 5.9% by quantity.