There's a common belief among bullion collectors, when in doubt, don't clean your coins. In general, a coin derives its value from the metal content of the coin itself, not its appearance or shine. That being said, some people want their coins looking brand new, and when selling on the secondary market, the look of a coin may impact its value.
As such, you might choose to clean your coins. If you do decide to clean your coins, however, you should use extreme caution. Some cleaning agents may do more harm than good, and if you scrub the coins too hard or clean them too often, you may actually shave away some of the metal in the coin. When in doubt, you could always pull out the phone book and do a quick internet search to see if there are any professional coin cleaners nearby.
First things first, if you are thinking about using a metal cleaner to clean your coins, don't! Metal cleaners contain abrasive chemicals, which will damage and scratch the surface of the coin. Some people think that since gold is a metal, and metal cleaners are designed to clean metal, it's okay to clean coins. It's not! Metal cleaners are meant for industrial metals, not bullion coins!
Also, do not use anything that might scratch the surface of the coin, as this can affect its by reducing the gold or silver content of the coin itself. This means you should never scrub a bullion coin. Not with a brush, abrasive pad, or even a soft towel. Any type of scrubbing can damage the surface of a coin. If you must dry a coin with a towel, dab, not scrub.
Also, you should understand that many traders and dealers actually prefer uncleaned and unpolished coins as it shows they are genuine. The simple fact is that coins will age over time. This is especially true for silver coins, which tarnish and gradually grow darker over time. Professional traders and dealers may actually check to make sure that a coin has not been cleaned, so keep this in mind!
So let's say your coin gets some dirt or other grime on it and you decide that you do want to gently clean it. The best thing to use is warm water and soap. Simply place the coins in the warm water and let it slowly dissolve any grime that has built up. You can also use gentle soaps or detergents, such as hand washing soap.
Another option that some gold collectors like to do is to put coins in boiling water. The fast moving water can dislodge residue and grime that may have built up on your coins. Due to gold and silver's high melting point, the heat should cause no damage. Still, you should carefully watch the pot to make sure the water does not boil out, and we recommend you only use boiling water if your coins are very dirty.
Many professionals believe it's okay use acetone and other solvents on gold, but you should probably not use them on silver. You should only use a solvent if there is a particular stain, such as adhesive residue, on the coin. First, however, try warm soap and water to remove the stain, even if it takes more time. If the stain can't be removed with soap and water, you can use a solvent to remove it. Remember to dab the coin dry, and afterwards wash it again with soap and water.
Sometimes people do not properly store their coins and they end up with rust spots on them. To be clear, gold doesn't rust, and while silver oxidizes, it doesn't produce a rust similar to steel. If you store your coins in an iron box, however, there is a chance that some of the iron could rub off onto your bullion coins and then rust. With gold, you can use vinegar to gently clean off rust spots. With silver, it's usually best to leave the coin alone because acids react more easily with silver.
The Best Solution