Why Does Silver Tarnish?
How do you keep silver clean and polished?
Silver is not attacked by air, but by your furnace-- coal and gas heating produces sulfuric acid which will attack the surface of your silver articles causing the metal to darken.
It's not just your silver, this happens to all silver, sterling and silver plate. In order to keep silver clean it should be stored properly stored in a dry place. Better yet, I would suggest using a pacific silver cloth (cloth impregnated with a chemical that prevents tarnishing).
How to Clean Silver and Silver Plate
All silver, whether sterling or silver plate, can be cleaned with any professional silver polish (not metal polish as it is too abrasive). Also never use Toothpaste for the same reason. Silver polish is readily available at most grocery Stores IE: Kroger, Albertsons, Publix etc. and in Jewelry Stores. Some of the brand names for silver polish are Hagerty, Wrights, Goddards, Weiman,Seige Etc.