I'm with @Lolli and @Severus Alexander. I don't see how it could be authentic in light of the other coins with the same flan shape and centering. If you didn't pay a fortune for it, I think that's a great idea. A forgery that passed undetected through so many experienced hands is unusual and interesting in and of itself! To give Lolli the benefit of a doubt, I suspect much of this perception is a language and culture issue. Subtleties of written communication are difficult to convey.