Probably a revenue, but hardly useless. They are quite beautiful and very collectible. There are websites online that catalogue these, though I have none available for you at the moment.
Actually a quick google search turned up this site.
Have a look through and see if you can find your stamp.http://eng.ssjp.dk/rev/eng/rev/overviewrev.html
Also heres a good thread from a year or so ago here on SCF about thesehttp://goscf.com/t/32506