Try this method if your 925 sterling silver jewelry has a lot of tarnish because it works really well. Begin by mixing half a cup of white vinegar with two tablespoons of baking soda. After that, soak your tarnished jewelry for two to three hours at the very least. If the mixture fizzes, don't worry; that's completely normal. You must protect your 925 sterling silver jewelry from certain outdoor activities, such as using it in swimming pools (because swimming pools have chlorine in their water), contact sports, gardening, and the gym.