Keep your sterling silver jewelry in an air tight plastic storage container or plastic zip-lock bag to preserve its original appearance. Sterling silver does tarnish over time, so storing them in plastic helps to slow this process down considerably.
What causes sterling silver to discolor over time? It is a natural process called oxidization. Oxidization is an interaction between air pollutants and other substances.
Clean your jewelry often. You can use a soft cloth and dishwasher detergent such as Dawn or liquid hand soap. If your jewelry has tarnished to the point that Dawn doesn’t restore it back to its original state, try using boiling water and baking soda. I found this information at http://www.beadingdaily.com/blogs/daily/archive/2008/07/30/at-home-tarnish-busting-remedies.aspx. This works perfectly. I used this method and it restored my jewelry back to normal. I deviated a little from what the article said, but received the same results. I put the water in a cup in the microwave (this saves time from boiling water on the stove), then put aluminum foil at the bottom of a plastic cup. I poured the hot water from the microwave in the plastic cup and then put my jewelry in it. I then poured baking soda in the cup. Enough to where I started smelling this nasty odor. When you start to smell the odor, you know that it is working. Let it sit until the tarnish comes off. Pour more baking soda if needed. Once the tarnish is off, I just got a soft cloth and water to wash the baking soda off of the jewelry.