I also think the problem here isn't the dark spot or the setting or anything in particular. You just don't like the ring (which is fine and I'm sure your experience with the original jeweller added to this) so I think you want to know how much you can sell it for and thus put it into a new ring?
I think the best thing would be to just get a whole new ring that seems the only option that will make you genuinely happy.
I think the best thing would be to just get a whole new ring that seems the only option that will make you genuinely happy.