Ginolerhino isn't implying it's a "
fake," only that it's possibly a barbarous imitation (which can be as interesting and, sometimes, more valuable than the original!). So don't worry about that!
I don't want to speak for anyone else, but I think the reason for conjecturing the coin might be an imitation is that the position of the spear seems to be a little lower down on the
face on the
obverse, and the lack of details on the
reverse. The dirt tends to spread and exaggerate the high points and cover the finer details of the coin, so it's hard to determine one way or another.
The coin is rather shiny, and I'm wondering if it's been waxed. Not a bad thing at all, but it does tend to make coins hard to get correct lighting on for pictures.
Have you considered further cleaning? A
good soak in
Gringott's and scrubbing might show some more detail and allow you to determine more of the details. Or do you want to leave well-enough alone?
For me, curiosity would get the better of me and I'd want to see what's under the dirt. But that's me ...
Good coin, in either case.
Tony