Specimen Stamps

Sometimes, when a stamp is issued, the postal authority will send samples to the press, museums or other countries. In order to make sure those stamps aren't used for postage, they are stamped as being a "Specimen" (In German, the word is "Muster"). They may also simply draw a diagonal line through a corner so as to not affect the viewing of the stamps's art.

Here are a few specimens I've been lucky enough to track down.