I have a collection of US gold coins bought around 1980. For the last ten years I had them in a safe deposit box, with each one in a standard plastic envelope; they were all in MS65 condition. I didn't realize the vault was not air-conditioned when the bank was closed. I have since moved the coins to my fire-proof gun safe in my home, but during their stay in the bank several coins picked up some kind of dark stain from the plastic envelopes (due to heat, I'd guess). What's the best way to get rid of the stain?
First, I'd say don't do anything to the coins yet. Cleaning more often than not reduces the value of a coin. However, if the coins are valued only for the gold, as in they're bullion coins, a light cleaning wouldn't devalue them. If there is numismatic value in the coins, cleaning almost certainly will devalue the coins. Could you give us an idea of what the coins are?
These are nuismatic coins. A couple of US $1, couple $5, couple $10 Indian head and some $20 double eagles. These are all uncirculated, and were in excellent condition before the stains.
I hope this standard plastic envelope you mention is not a coin flip that contains PVC. Can you describe this envelope for us ? Based on what your answer is - your best bet may be to send the coins to NCS for conservation. I would not - repeat not - try to do anything to them yourself.
Yes, I agree with this, except that I'd recommend to show them to someone locally to see if sending them to NCS would be a good idea first. Any coin clubs in your area?
I am Dallas, TX. I suppose there might be a coin club here. There's certainly some dealers. The envelope is stiff, clear plastic -- the same one the coin came in.
OK - you say the flip is stiff - this is usually a good sign as the PVC flips are soft & pliable. Now as to the spots - gold does tone at times. So it may be toning on the coins. This is not always a bad thing as some collectors like toned coins. These stains - are they a copper color ? Many gold coins will develop copper colored spots given the right conditions - heat, humidity etc. On other gold coins the toning just turns certain areas of the coin a darker color. Can you post pics of the coins for us ?
Standard advice not to clean coins. But, if it is PVC you should do something with it. There has to be several place in Dallas that you could bring them to for evaluation. Isn't Heritage downt here somewhere?
The stains are dark brown -- almost black -- large spots. I'll see if there's somewhere in Dallas I can take them.
