I'd say you can do both. But wearing Ruthenium Polymer Coating does not make you exactly invisible. I used to imagine the effect to be a little like in Predator, if you know what you're looking for, you can see it, though to see it when distracted is unlikely, and it is hard to keep track when it is moving and darting in and out of cover. Also, most armor does not cover all parts of the face. So I say whatever little visible residue remains, the spell doubles it.