Sorry Sword, but I don’t agree with the definitions above, particularly with “conservation’ which almost never involves removing an original surface, but entails removing foreign matter, contaminants, corrosion products etc to reveal the original surface and possibly with archaeological finds for example treatment to prevent/ deactivate future or active corrosion eg rust, verdigris, treatment which may be physical, chemical or by environmental control.
The act of repairing damage, a mount mark, piercing, scratch etc, would be better described as restoration, in that the actual object is in some way modified to ‘enhance’ it’s appearance, albeit that the intention is usually to return it visually to a previous state.
What we generally refer to as cleaning of coins does usually involve removing something from the original surface, be it by abrasion using polishes (or wire wool or sandpaper for example -shudder-) or by chemically as with silver dip; some might argue the latter only involves removal of corrosion products ie tarnish, but in effect dipping facilitates metal loss by removing a protective coating and exposing environmentally reactive fresh metal which then in turn will tarnish over time.
There is certainly overlap between the above and room for interpretative differences. Personally I do advocate coin conservation where necessary, for example removal of acidic oils and waxes to prevent future corrosion, or removal of active verdigris to keep the damage localised. And I see so many slabbed coins with dirty, gunged up letters or designs- there is no point placing the coin and the causes of corrosion in the same ‘protected’ environment.
Jerry