Roman States Scott #15 (A15) 10 Cent Black, Vermilon, Imperf 1867

It could be the late and last 1870 issue when the colors changed considerably thus this dull stamp...

As I said, I do not treat it as genuine nor do I think so.

It is an article of faith among stamp collectors that many of us can say "that's probably a forgery" based on any number of known characteristics, but very few of us can safely say "that's genuine."

I only buy Roman States under the "maybe" category of educated guessing. Life is too short to get a cert for everything. (And if you care that much about Roman States, I'm guessing you'll eventually know enough to not need a cert.)