Special 20 cent coins: Rare misminting brings 825 times the value. For example, a 20 cent coin from 2002 from Italy was accidentally produced without the characteristic ripples on the edge.
Some 1 euro coins can also fetch thousands of euros - as can certain 50 cent coins. Anyone who discovers an incorrect embossing can try their luck as a private seller on the Internet - and use the prices of other offers as a guide. If you still have old currencies at home that are no longer used as a means of payment today, you may have a little treasure lying around.