Hey I have a silver 1982 coin from Yugoslavia,my grandma left it to me Im wondering can I clean these black spots on it and why did they showed up
Try soaking it in pure acetone (not fingernail polish), giving it a good rinse afterward. The coin appears to have been harshly cleaned, so I assume you want to save this coin for sentimental reasons. Chris
It is a memory on my grandma and a part of my coin collection and its "rare"(these were given to "best" teachers as award)so theyre not that common and I dont want to damage it
First, you'll need to face reality. The coin has been cleaned. The spots have etched into the surface. Acetone will not help; however, it will not hurt either. Soak it and there is a 2% chance the spots will lighten. You can send it to NGC for conservation if you wish. They may be able to improve it but its value as a coin is already ruined, even if they are able to remove the spots.
I agree with the comments that there's not much you can do, short of dipping the coin. And even that may or may not remove the black spots still present. And I say still present because it is my guess that at some point that coin had a whole lot more black on it than you see now. And the harsh cleaning that was obviously done was done in an effort to remove that black or at least some of it. As for what caused the black, I suspect environmental contamination of some kind. Some kind of something got on the coin probably in the course of storage and caused the metal to corrode. And when it was noticed, somebody tried to get it off resulting in what you see now.
The reason people say your coin was "cleaned" or "harshly cleaned" is the presence of all the parallel (or near parallel) lines. Chances are that you are not going to do any more damage to the coin than has been done, so.... The spots might be able to be removed with a sharp instrument and picking or prodding at them. I would start off with a toothpick and a magnifying glass and try prying one of the spots off. You could move up to harder substances (a rose thorn is the classical instrument) but if you try a steel pin or needle, you need to be VERY careful because this is harder than the coin material. Let us see how it came out if you try it. Soaking it for a couple of days in distilled water or acetone might help soften the spots up.
I would rather that you try to spot clean your coins. For silver or the like, I found that covering the black spot with pure honey works, and wait for the carbon to soften before picking it with a toothpick, taking care not to scratch the very surface of the coin. Peel off the black material and repeat the application of honey as needed. The blackened spot may have cuds that make them susceptible to the accumulation of grime and dirt, so check your coins and handle with clean hands at all time. Keep it dry with a soft cloth. By the way, your coins are beautiful, so do not ever soak them in harsh chemicals. Just let it tone and acquire a patina, which collectors love.