@BBC, yes I agree with @TT that your coin appears to have some surface staining just to the right of the mm. From your pics, it looks like this area isn't raised above the surface of the surrounding field.
"If you climb a good tree, you get a push."
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz