Initially it was decided that the country specific sides (National Sides) of the Euro coins could not be changed. This decision was reversed in 2004, most probably to allow Greece to issue a special coin for the 2004 Olympics which took place in Athens.
At any rate Greece was the first country to issue a commemorative coin and in fact in 2004 Greece minted no ordinary 2 Euro coins but only 2 Euro commemoratives.
The decision giving rise to the commemorative issues is, from the point of view of collectors, a very welcome one as undoubtedly some of the most interesting Euro coins are to be found among the commemoratives.
About 120 Commemoratives have been issued up to the present (2012).
The new freedom to issue commemoratives was however circumscribed with certain conditions and recommendations.
Firstly to preserve a sense of continuity and to avoid the general public becoming confused it was decreed that the country specific side (National Side) could not be changed before 2008 unless the head of state depicted on the coin should die beforehand. (This did in fact happen in the case on Monaco and the Vatican).
Initially each country could only issue one commemorative per year.A
decision reached in July 2012 however allows 2 commemorative coins per
year to be issued as from 2013.
The number of commemorative coins issued by any country in a year is restricted to
the larger of:
a) 0,1 % of the total number of 2 Euro coins in circulation in the whole Euro zone.
(this limit can be increased to 2 % if an event of special significance is to be
commemorated but then the issuing country may not issue any furher commemorative 2 Euro coins for four years).
b) 5 % of the 2 Euro coins already minted in the country issuing the commemorative coin.
There have been three general commemorative issues - where the coins were issued by all members of the European Union who are also in the Euro zone.
2007 - commemorating the signing of the Rome Agreement.
2009 - commemorating 10 years of the European customs union.
2012 - commemorating 10 years of the Euro as the official currency.
The design on these issues is the same for all countries, the name of the issuing country is however also shown.
Shown below are the issues for Luxembourg. These differ from those of the other countries because the law of Luxembourg requires that the effigy of the reigning monarch appear on all coins. This has been taken into account by imposing a latent image on the coins. This means that if the coins are viewed from a particular angle the image of Prince Henri can be seen but otherwise not.
2007 - The Latent Image is within the small circle to the left of the inner ring.
2009 - The Latent Image extends over the whole of the inner circle.
2012 - The Latent Image is confined to the small circle formed by the Euro sign in the middle of the coin.
States were allowed to issue their own national commemorative 2 Euro coins in these years - so in effect the (then) rule allowing only one commemorative coin per year was relaxed in this instance.
Note - These general commemorative coins were not issued by Monaco, San Marino or the Vatican as, although they are in the Euro zone, they are not members of the European union.