After a while, real silver oxidizes and turns dark. This is due to the combination of silver with oxygen and hydrogen sulfide.
With a few home remedies you can quickly get tarnished silver fresh and shiny again. Cutlery to jewelry: Simple home remedies to clean tarnishedsilver. Cola or beer as a cleaner for dirty silver? Put a large sip of cola in a bowl and place the silver jewelry or cutlery in it overnight. The next morning the discoloration should be gone thanks to the acidity.