With all the interest in toning I assume anyone owning shares in metal polish manufacturers will be panicked !
If you drop oil or gasoline onto a pool of water you will see wonderful rainbow colours but if you were thirsty would you drink this water ?
Not sure I see the interest in polluted / chemically oxidised coins.
If you want to ruin your silver you can possibly barbeque it or try heating your coins in a container with either tobacco or sulphur. Should give you that sought after toning!
Sorry stackers but this toning thing in my opinion is utter crap. Silver has an exceptional high reflectivity and therefore can appear shiny like a mirror. Anything else is just contamination but to some, might be construed as art.