I saw this thread when it was first posted lastnite, my first thought was "that's not an S, it's an O."
Yeah, that makes sense ...an "O" mint mark with the notch of the top serif of an "S" which it cannot be because it's an "O" right? Wait...perhaps it is an "O" with PMD at the top so it looks like it might be an "S."
One way to be sure is to match the coin to a known VAM. Of course that would take a full photo. I see doubling in the E of ONE so I know there has to be a match somewhere.
Guys, that's an S. The serifs are plainly visible. There's no question about it. In fact, it even appears to be an rpm
You'll need to wait until next week. Then I'll check VAMWORLD to ...wait a minute You got me. Why don't you humor yourself and check Vamworld.
Got some photos: One is an RPM on an 1890-S $. The other is a "filled" mint mark on an 1878-S Trade $. Note how the "filling" on a "filled" mintmark DOES NOT spread outside the "S" like the damaged "S" above does. Hope this is helpful...