1 Euro Cent Pattern

Slovakia joined the European Union in May 2004, and that year a series of euro cent patterns was produced in anticipation of eventual eurozone membership — which didn't arrive until 2009. These 2004-dated pieces were never intended for circulation; they were struck to test designs and satisfy the EU's approval process for candidate nations.

The five-year gap between pattern production and actual adoption is longer than it might appear. Slovakia had to meet strict convergence criteria, and the 2004 patterns predate the country's ERM II entry by two years.