Top 7 Ways to Ruin Your Coins

Never Do This to Your Coins!

no cleaning coins
Getty Images/nemoris

Coin collectors like to show off their coin collections to other collectors and friends. At the same time, it is possible that your actions and displays may be harming your coins. Here are seven ways that coin collectors can ruin their coins without even knowing it. I've even seen expert coin dealers spitting on their coins without even knowing it.

If you want to protect the investment that you are making in your coin collection, then take the time to learn how to handle them properly, clean, store, and protect your valuable coins. Otherwise, your coin collection will be worth much less when you or your heirs go to sell them.

  • 01 of 07

    Touch Your Coins

    Hands with coins
    Verity Jane Smith/Stockbyte/Getty Images

    Just touching your coins with your bare fingers may be enough to damage them. High-grade rare coins are especially susceptible to damage from the touch of your finger. It is possible that you will damage your coins if your fingers come in contact with mint state and Proof coins. Your fingers contain oils, acids, and minuscule pieces of grit that will adhere to the surface of the coins and cause them to discolor or suffer microscopic scratching. When you handle your coins, wear cotton, Nitrile, or latex gloves, and handle the coin only by the edges.

    It is also possible to damage your coins if you drop them on a hard surface. Therefore, hold your coins over a soft cloth or pad as you are working with them. As soon as you are finished, you should return them to a proper coin holder.

  • 02 of 07

    Clean Your Coins

    Cleaning coins
    Getty Images/nemoris

    Except for coins freshly dug-up out of the earth from a metal detecting find, cleaning or polishing your coins will do more harm than good. Once you expose the metal to the air, it is natural for it to oxidize, or tone. If you strip the coin of this toning, not only will you lose any remaining mint luster, the coin will appear harsh, unappealing, and suffer microscopic abrasions that will lower the grade of the coin. Additionally, toned coins are worth more than coins that were stripped of their original toning.

    There is an area of numismatics known as coin conservation. Coin conservation differs from cleaning in that conservation does not disturb or remove the molecular structure of the coin at the surface. In other words, proper conservation will remove contaminants from the surface of the coin without disturbing or removing a single molecule of metal from the coin. If you really must clean them, clean coins safely.

  • 03 of 07

    Spit on Your Coins

    A man's mouth
    Getty Images/Image Source

    Talking about your coins can do just as much damage as touching them or cleaning them. If you leave your coins exposed while you chatter away little bits of saliva that escape from your mouth when you talk will land on your coins. These microscopic bits of saliva can cause spotting and discolorations that are difficult to remove. Collectors have ruined many circulated, Proof and Mint State coins this way. Say whatever you want about your coin collection, just make sure your coins are away from your mouth when you say it.

  • 04 of 07

    Break Their Holders

    a cracked out coin from a PCGS encapsulated slab
    James Bucki

    You are certain to greatly decrease the value of your mint set, Proof set, commemorative coins or encapsulated coins by removing them from the mint-issued holders they come in. The holders, along with the box and literature (if any) are part of the "set" and should be kept intact and pristine. Similarly, coins that have been slabbed by third-party grading service are worth a premium in their protective cases. Never remove coins from these types of permanent holders unless there is a specific reason that would justify the coin being cracked out of its slab. However, some early sets issued by the United States Mint before 1955 came in paper envelopes that contained acids or plastics that degrade over time. It would be wise for you to remove these coins from these original holders before they get damaged.

    Continue to 5 of 7 below.
  • 05 of 07

    Expose Them to Acid

    coins in a paper envelope
    Coins stored in a paper envelope can ruin your coin collection. Christopher Stevenson/Getty Images

    Storing your coins in paper envelopes with your notations beside the coins, or in cardboard boxes is a good way to damage them unless you are careful to use acid-free paper materials. Over time, the paper material breaks down, releasing acidic chemicals around your coins. This acid will cause spotting, discoloration, and can promote oxidation (toning) of your bright, mint surfaces. Be sure to buy only acid-free paper and cardboard supplies to store your coin collection.

  • 06 of 07

    Coat Your Coins in Green Slime

    PVC Damage to Coin
    James Bucki

    Another good way to cause spotting and degraded the surface of your coins is to store your coins in PVC-based plastic flips, holders, and boxes. Similar to the way the acid in the paper can harm your coins, the chemical by-product of certain plastics can damage your coins over time. If you store coins in those handy food-grade plastic containers, or soft, pliable coin flips, your coins will eventually develop a slimy green coating on their surfaces which will damage them permanently. Be on the lookout for coins set issued from mints around the world that came in coin holders that contained PVC. These coins should be promptly removed from these holders before they get damaged.

  • 07 of 07

    Expose Them to the Elements

    a picture of an old attic with toys and boxes
    Storing coins in an attic or basement will ruin your coins. Steven Gottlieb/Corbis Historical/Getty Images

    If you store your coins in the attic or basement, you are probably exposing them to extremes of temperature and humidity that will promote their oxidation. Also, these conditions will quickly break down the storage materials (such as flips, paper envelopes, cardboard holders, plastic containers, etc.) that hold your coins. To protect your coin collection, it is best to store it in a dark, dry, temperature-controlled environment such as a safe deposit box or specialized coin cabinet.

    Edited by: James Bucki