Accidentally exposing your coin collection to the elements can ruin them, which may include storing your collection in extreme temperatures or humidity. Basements and attics are the worst place to store your coin collection because of the temperature and humidity can cause oxidation to gather on your coins. These types of conditions can also cause storage materials to break down quickly, which can include plastic and cardboard containers.

Cleaning your coins can do more harm than good, because if the toning of a coin is stripped, then the coin will forever appear harsh and unappealing. Your coins will lose their luster and can even suffer from scratches and abrasions while being cleaned. Once any type of metal has been exposed to the air, then it will begin to naturally oxidize, which in turn can cause your coins to deteriorate.

Simply touching your coins directly with your bare hands can cause severe damage to them due to the oils and acids on your own skin. Tiny particles of grit and oil can be transferred from your skin onto your coins causing them to suffer from tiny scratches and possible discoloration. Whenever handling your collection be sure to wear either cotton or latex gloves and even then only handle the extreme edges of your coins.

If you purchase a mint set, proof set, or uncirculated set of coins and remove them from the holders that they came in, then you will definitely decrease their value. These holders should always be kept intact with their coins untouched by the human hand. Protective cases likes these have been specially made for these type coins as their permanent holders.

When storing your coin collection it is best to store them in a dark and dry environment, preferably one that has its temperature controlled. Envelopes or wrapping your coins in paper is a really great way to damage your collection, unless you are certain that the paper materials you are using are completely free of acid. Paper material over time will break down and then will release an acidic chemical onto your precious coins, which can cause spotting, discoloration, and will even promote toning or oxidation of their surfaces.

Speaking above your coins can cause little bits of saliva to escape from your mouth unnoticed. This also will cause spotting and discoloration and are extremely difficult to remove from the surface of your coins. Another way to cause spotting that cause the surface of your coins to become damaged if to use PVC based plastic flips, boxes, or holders.

A chemical product on certain types of plastics has been shown to damage coins over time. This chemical will eventually develop into a slimy green coating that will cause your coin collection permanent damage. So those little plastic food containers may be great for storing your food in, but they can ruin your valuable coin collection.