And, I broke down and CLEANED the coin; used DAWN dishwashing liquid (hey, it's used on birds and other creatures after OIL SPILLs, so WHY NOT?) HERE are the results. Features that were readily READABLE have now been erased; am NOT totally happy with the results.
Congratulations.. you took an entirely original and problem free coin, and washed it. You've removed all of it's history and character, and left behind a generic, cleaned, dull, boring coin. This now-recently-cleaned coin is stripped, washed, and completely undesirable compared to what it was. It wasn't a terribly high value coin to begin with, but you've just cut it's value in half. Let this be a lesson to anyone who wants to wash their coins. Just don't do it!