I agree some of the details of the coin are now better in appearance.
Had this object been a valuable piece at a museum or gallery and deemed in need of restoration they may have used the same or some similar chemicals. The difference would be that it would be done a fraction of an inch at a time, removing only what was absolutely necessary for the desired results and may have taken several months to accomplish.
Quote:
NEVER clean a coin!
Don't confuse ancient coins with modern coins; ancient coins are always cleaned to some extent.