Thoughts on artificially toning coins?

From what I’ve seen, artificially toning coins is really controversial in the numismatic community. On one hand, it adds beauty (and sometimes value) to a coin, and on the other hand it can be seen as ‘ruining’ a perfectly good coin or even used for malicious purposes. In my opinion, it’s fine to do on common change or silver coins only worth their metal value, but I do think an artificially toned higher value or graded coin has been effectively ruined. What are your thoughts on this?

And while you’re here, do you have any tips on toning copper/copper-nickel? I might tone some coins in my change. And can anything without copper or silver content be toned (nickel, stainless steel, aluminium etc.)?

I admit I have played at this game, with nothing to show that I am proud of.

As I said, you should pretty much only tone very common coins. Anything else is either a waste or blatant doctoring.

Always wanted to give a try to the artificial toning thing but I never find the time to try it with some kind of copper coin like a british penny or something like that

I’ll probably use some of the large British pennies for toning as well.