::Brass:: is an alloy of copper and zinc and will naturally tarnish when exposed to oxygen. Some people like the patina of tarnished brass and the tarnish is actually a protective layer for the brass, but if you want to get the shine of the new brass it's pretty easy to do with some typical household products.
If the tarnish isn't too pervasive take about 2 tablespoons of baking soda and add drops of lemon juice - from concentrate is fine - until you have a nice paste. The lemon juice will bubble and fizz as you add, don't worry it'll stop after a second or two. Take an old toothbrush and apply the paste to your piece and scrub. Let it sit in the paste for about 30 minutes and then rinse it with water and dry it thoroughly.
If the piece is heavily tarnished or the above doesn't work, you can place the piece in vinegar and let it soak for 30-60 minutes and then scrub it with an old toothbrush. Once clean, rinse it with water. This cleaning method is more aggressive and may leave the piece more "raw" looking - it won't have as warm of color until the patina rebuilds.
Oils from your skin and the oxygen in the air are what accelerate tarnishing. If you want to slow the tarnish process, wipe the piece with a soft cotton rag after wearing and store in a plastic bag with an anti-tarnishing strip. You should have received one of these with your piece.
::Silver:: tarnishes when exposed to certain elements, thus it pays to use this precious metal in appropriate places. As part of best practice, sterling silver manufacturers don’t recommend the use of silver inside the shower, in pools, ocean, inside a sauna or even a hot tub. The high chlorine content and even the minerals found in swimming pools can hasten the development of tarnish, thus tarnishing the silver.
How to clean and remove the black tarnish
Sterling silver can be cleaned and maintained in a variety of ways. A simple yet effective way to clean silver is through the use of aluminum foil and baking soda. Simply place a double layer of foil in the bottom of the pan, add warm water and at least 2 tablespoons of baking soda. Once the mixture is complete, you can now place the silver jewelry into the pan so it will get in contact with the foil. Let the silver soak in the mixture for a few minutes, rinse and polish it off using a clean cloth to transform its looks. There are also products that are formulated to clean the tarnish, from silver polish to cloth.
Another tried and tested approach is to wear it often- it works and allows you to show off your style in every occasion. But don’t forget to store the silver in appropriate places when not in use. You can store sterling silver in a pouch or find a separate place in your jewelry box.