Unless you seal away your valuable silver coin collection in airtight bags or containers and out of sight, your coins will tarnished. The tarnish results from a reaction of the silver and sulfur in the air combining. The best way to clean silver coins is to do it gently so as not to damage the coin, and by using a method that allows you to manage just how much tarnish is removed. Some coins look better and are even more valuable with tarnishing. Depending on the coin you may only want to remove a small amount of the tarnish.
Mix a lemon juice bath for the coins in a plastic container by making a solution of approximately ½ lemon juice and ½ water. If after using this mixture you are not satisfied with the amount of tarnish removed you can choose to use straight lemon juice.
Let the coin soak for 15 minutes at a time. By soaking the coin in short increments you can control how much tarnish gets removed.
Remove the coin and scrub gently with a soft toothbrush. Put the coin back into the lemon bath for another 15 minutes if you want more tarnished removed.
Rinse the coin in water once you are satisfied with the amount of tarnish removed. Dry it with a soft washcloth.