How many times has this happened to you, you buy a piece of sterling silver jewelry, wear it a bunch, then over time you forget about it and leave it on your nightstand, and rediscover it months later, only to discover that it's turned black? Not to worry! There are several ways to get your jewelry back to new.
The first thing you'll want to determine is that it is in fact sterling silver. One of the best ways to do this is to look for a stamp on the back or the inside of the ring shank saying "925" or "sterling". A piece may still be sterling even if it doesn't have a stamp, so the best way to determine if it'll polish up is to do a spot test in an inconspicuous area. If it's not sterling silver, best case scenario it won't polish, but worst case scenario, it's not actually tarnished, but in fact losing its plating, which isn't reversible. You can get it re-plated, but for most costume jewelry, it's not worth the cost.
Once you're sure your jewelry is sterling silver, it's time to figure out the best way to polish it. If it used to be bright and shiny, and doesn't have soft stones like opal, turquoise, coral, or pearl, you can usually just dip it in a tarnish remover like Tarn-X. This is the quickest and easiest way to remove tarnish, but I definitely recommend doing a spot test first, because it can be intense! I can't stress enough that this is NOT for every piece. You can find Tarn-X at most drugstores or here.
If your silver jewelry has a lot of components or texture, where it was antiqued to bring out the details (think vintage southwest turquoise jewelry), you won't want to dip the piece. First of all, the chemical will damage the stone, and second, dipping the piece will remove all the oxidation, even in the nooks and crannies where you want it to stay dark. In this case, you'll want to use a polishing compound-infused cloth. That way, you can buff the high points back up to a bright finish, but the details will remain dark, preserving the high contrast finish. This is the safest method, if you're concerned about damaging your jewelry. You can get polishing cloths at most jewelers, or here.
With jewelry that is oxidized intentionally, like my oxidized and ombre pieces, don't try to polish them at all! It will destroy the dark patina.
Gold jewelry may dull slightly over time, but it doesn't react with the air the same way that silver does, and it should stay bright and shiny much longer with minimal polishing.
With these simple steps, you can restore your silver jewelry to a gorgeous shine, but the best way to keep your jewelry looking great is to wear it often, and when you're not wearing it, keep it in an airtight box or bag, and give your pieces a quick polish frequently with a soft cloth to prevent excessive tarnish buildup. Use anti-tarnish strips in your jewelry box to help prevent oxidation. You can get them here.