Coin collectors do things that can mistakingly ruin their coins. If you care about your investment of rare coins, it is important to take the time to understand how to properly store, protect, clean, and handle your rare coins. Here are some common mistakes:
1- Touch your coins: Simply touching your coins with your bare fingers is enough to damage the coins, especially the higher grade ones. Fingers contain oils and minuscule debris that when touching coins can cause them to become discolored and have scratching. It is important to wear cotton or latex gloves and only handle the edges.
2- Clean your coins: With the exception of recently dug-up finds, cleaning or polishing coins will do more harm than good. Once it is exposed to air, it is natural for it to oxidize or tone. The coin will then appear harsh and unappealing.
3- Spit on your coins: Talking about your coins and having little bits of saliva land on them can cause just as much damage as touching them or cleaning them. It is important to make sure your coins are protected while you chatter away about them!
4- Break the holders: You can greatly decrease the mint set and proof set coins by removing them from their mint-issued holders. The sets should be kept intact and pristine.
5- Expose them to acid: Storing your rare coins in envelopes, paper, or with notations beside them is a good way to damage them unless you are careful to use acid-free paper.
6- Coat your coins in green slime: Storing you coins in PVC-based plastic flips, holders, and boxes can cause spotting and degraded surfaces. If you store coins in food-grade plastic containers, or in soft, pliable coin flips your coins will eventually develop a slimy green coating that will damage them permanently.
7- Expose them to the elements: If you store coins in the attic or basement, then you are exposing them to the extremes of temperature and humidity that will oxidate them. To protect you collection the best, store in a dark, dry, temperature-controlled environment.