to restore or not to restore...

[gp]

Originally Posted by fernando

Coins, stamps and antique weapons are certainly not the same thing.

I would not know a stamp can be restored; it surely demands high expertise.
But i have gathered coins for a couple years (before i sold them to afford gathering antique weapons). While restoring coins, for what the strict term means, is new for me, the act of cleaning them, as presently said not to adviced, is unclear for me. I took it that coins are classified by the integrity of their graphic or pictorial contents, as well as their metal structure. The various catalogues i knew available defined their such condition in (at least) four different grades, from scrap to pristine, and respe tive collecting & market value. But i have never heard that cleaning (read washing) the dirt of a coin would 'damage' its value. But then, i have never nagivated in a high end collecting universe, and therefore i ever ignored what was prohibited .

No problem and no offence intended but first hit on google:

"It is best not to clean rare coins as removing the patina can significantly reduce the value of them. For this reason, most coin hobbyists almost never clean their coins. In fact, 99% of coins do not increase in value after you clean them, but many will be greatly devalued.6 sep. 2020

also:

https://coinvalues.com/library/why-y...ean-your-coins
https://www.youtube.com/watch/uljNQ5mMJ98

from own experience I can give examples like lower silver graded coins like the late Illyrian drachmes, late Andalusian Dirhams, late Ottoman Akces, Riga Shilling from Sweden (Kristina) some late Medieval Balkan ( Hungarian, Serbian, Bosnian) next to modern (post 1850) machine struck coins lose their original color.
Auction houses, sellers and serious collectors in the UK, Netherlands, Germany, Austria and USA will refrain and advise against it. Some countries ( Belgium does clean ) accept it as long as the struck print is not affected.

High garde silver and gold ones can be cleaned but again... losing the patina = losing value and if needed one needs to do it carefully with expertise.

As for what to do: it's all in the eye of the beholder at the end...

as for " restoring coins, for what the strict term means, is new for me " many coins ( silver, gold) have been used as dowry, hence holed to add them to a chain, bracelet, headdress and later "repaired" by filling the hole with gold and or silver to its original state.
Especially the Thaler through all of Europe or closer home for you your Reis and Reaals from Fernande I to Manuel I...