Euro is the name of the common European currency, adopted by 17 members of the Eurozone monetary union, as of May 2011. Its denominations include the 500, 200, 100, 50, 10 and 5 euro banknotes, as well as coins valued at 2 euros and 1 euros, and 50, 20, 10, 5, 2 and 1 cents. Each coin has distinct specifications, making it easy for visually impaired people to use them and difficult for criminals to forge them.
Euro coins are divided into three categories based on the metals used to make them. The smallest denominations (1, 2 and 5 cents) are made of copper-covered steel and easily distinguishable by their red color. The 10-, 20- and 50-cent coins are made of Nordic gold, giving them a golden color. The bi-color 1 euro and 2 euro coins are composed of several metal alloys, with the latter made of copper-nickel on the outer ring and successive layers of nickel brass, nickel and nickel brass again on the inner part. The 1 euro coin consists of nickel brass on the outer ring and layers of copper-nickel, nickel and copper-nickel again on the inner part.
All coins have a distinct size, both in terms of diameter and thickness, with the exception of copper coins, that have the same thickness (1.67mm). The 2 euro coin has a 25.75mm diameter and is 2.20mm thick, while the respective values for the 1 euro coin are 23.25mm and 2.33mm. The 50 cent euro coin's diameter is 24.25mm and its thickness is 2.38mm, the 20cent coin measures at 22.25mm diameter and 2.14mm thickness, while the 10 cent coin is 19.75mm wide and 1.93mm thick. The diameter of copper coins is 21.25mm for the 5 cent coin, 18.75mm for the 2 cent coin and 16.25mm for the 1 cent coin.
The weight of the 2 euro coin is 8.5g, approximately 0.3 oz., while the 1 euro coin's weight is 7.5g (0.27 oz). The Nordic gold coins' (50, 20, 10 cents) weight is 7.8g (0.28 oz), 5.74g (0.2 oz) and 4.1g (0.15 oz), respectively. For the 5 cent coin this figure is 3.92g (0.14 oz), the 2 cent coin weights 3.06g (0.1 oz), while the 1 cent coin weighs 2.27g (0.08 oz).
Euro coins are also different in terms of their edges' shape, with the 2 euro coin's edge being fine milled and featuring stars or letters, depending on the country of issuance. The 1 euro coin features an interrupted milled edge (smooth at some parts and milled at other), while the edge of both the 50 cent and 10 cent coins consists of fine scallops. The edge of the 20 cent, 5 cent and 1 cent coins is plain, while the 2 cent coin's edge is smooth with a groove.