u/ontheridgestamps

Fournier/Hirschberger forgery of the high value 5f stamp from the French Offices in Canton series of 1901. (Scott 14, Yvert 16, CV $250 mint hinged USD if genuine). Pretty much all of the French colony stamps of this design were forged by Fournier and circulate widely. I've found them in all sorts of purchased collections.

They are pretty easy to distinguish based on some key characteristics, although scans often aren't good enough to tell when you're buying online. A couple things to check - the genuine have more detail for the fingers of the two hands on the flagpole, and the bottom left piece of fruit in the "horn of plenty" at upper right is separated from the horn itself.