It is coincidental that a printmaker’s single colour choice is often prussian blue and that this happens to be one of my favourite painting colours.   Keeping the inks simple is best for me at the moment whilst trying to get the shade via the texture right, as well as the consistency of the ink, the paper and the press!  Prussian blue’s history is extremely varied; if you are mad about colour history there is plenty of very interesting facts about Prussian Blue here.