Cleaning a red copper coin

[thelawnet]

Here's the coin I bought:



Here's the one I received:



To be clear, the image is accurate. I tried scanning the coin myself, and it looks the same. A photo from different angles, with or without flash gives different results. I guess the bright light of the scanner hides the ugly stain.

The black stain is VERY noticeable in hand (I can't see the apparent red stain at all).

Is there a chemical I can soak the coin in to clean it, bearing in mind I want to retain the red colour?

[Samuel Tan]

I hope I am not o late.
Don't spend time to clean it. I assumed it is 1945 Netherlands Indie.
I have many of them, never been cleaned! But as good as it is. It came from the rolls.
So the coins never get exposed until I got them. The paper wrapper was falling apart, so I removed them. It is in (near) Un-circulated condition. I am not a grader, but a collector. I am in the process to scan them for swap.
Samuel Tan

[bruce61813]

The stain looks like it was against another coin or metal type with moisture present. Just a guess on that part. I would just leave it exposed to air and sunlight to oxidize evenly. Then put it into a conservative, acid free holder. If there are others that are still bright, I would used something like 'airtite capsule' holders. They are airtight and will keep the coin protected, but can be opened fairly easily.

Bruce

[Figleaf]

Samuel is quite right. If this is a 1945 coin, it's easy and cheap to replace it with one that is immaculate.

Peter