I don't know enough about artificial toning to comment.
But there may be evidence of cleaning obv. In the first photo there are what appear to be abrasions running left to right at the top of the star.
In the third photo there are similar streaks running SW to NE. (I suppose these could also be die polishing marks?).
And the fields are noticeably brighter than the areas with the devices.
Maybe this was a darkly patinated coin that a previous owner tried to clean obverse, was unhappy with the result, and tried something different reverse? Alternatively, the coin might have been stored with the reverse contacting something that led to an uneven patination. I have UNC bronze coins that were probably stored with a rubber band around them, leaving a black stripe across a bright orange obverse surface.
Edited by tdziemia
09/24/2019 08:04 am