1£ 1992 - proof

[freddurst]

I recently bought 1£ -1992 proof oak tree reverse. The coin was in BU condition- perfect coin. I put the coin in one coin hold - the self-adhesive ones.

In just one day I notice that some rainbow spots have appeared all over on both side of the coin. I didn't notice them when I received it , so I suppose that I did something wrong to the coin when I put it in the holder.

Could someone help me to understand what is wrong with the coin?

I'm sorry if this is a stupid question, but I'm still beginner in this area.

Thanks in advance.

[Colin G.]

I recently bought 1£ -1992 proof oak tree reverse. The coin was in BU condition- perfect coin. I put the coin in one coin hold - the self-adhesive ones.

In just one day I notice that some rainbow spots have appeared all over on both side of the coin. I didn't notice them when I received it , so I suppose that I did something wrong to the coin when I put it in the holder.

Could someone help me to understand what is wrong with the coin?

I'm sorry if this is a stupid question, but I'm still beginner in this area.

Thanks in advance.

There could be many reasons for the effect you are getting, some are:

How did you handle the coin, if your skin came into contact with the surface of the coin, this can start a chemical reaction, which can result in fingerprints/smears becoming visible. Ideally proofs should only be handled with cotton gloves or very carefully at the edges (not ideal), or through a cotton cloth (although there is more of a risk of dropping the coin).

What brand/make of holder have you used? Some of the cheaper holders are suitable for circulated coins, but again can start reactions on proof coins where the clear widnow becomes pressed against the surface of a coin.

How was the coin sent to you? Was it housed in anything that could have started a reaction?

Are the marks definitely on the coin and not from a smear on the holder itself?

There may be other reasons, but answers to the above may give an indication why.

[freddurst]

I received the coin in a plastic wallet pocket by mail. I didn't used cotton gloves but I held the coin only by the edge and i put it in this 2x2 holder right away after I opened the letter.

I really don't know the brand of my holders but I guess that they are not expensive, I bought them for 10p each. Those rainbow marks are definitely on the coin, because I opened the holder to replace it. First I though that it might be from the holder but I wasn't.

It is possible the difference in the temperature to be reason for that? And can I reverse the process?

It those rainbow mark reduce the future value of the coin?