To remove tarnish:
To remove tarnished appearance from your jewelry that does not include soft gemstones, pearls, or crystals, place your jewelry into warm water lathered with mild dishwashing liquid. Some of the recommended products would be Dawn, Ivory, or Simple Green. Do not use toothpaste or baking soda to clean your gold. Even though your gold has been hardened by infusing with other metal alloys, it is still a soft metal and can be easily scratched.
Once the jewelry is soaked in the warm soap lathered water, you can rub gently with your fingers or cotton swab. You can also brush lightly with a soft baby toothbrush only if more abrasive cleaning is required. ?When all the cleaning is done, rinse your gold jewelry thoroughly with warm running water and dry it with a cotton cloth. Do not use paper products such as tissues or paper towels because they contain particles of wood that can easily scratch the gold's surface.
Before storing, let the gold jewelry lie flat and air dry completely, overnight if possible. Moisture speeds the tarnishing process so it's important to make sure your gold jewelry is dry before putting it away. Once the jewelry is dry, if it looks dull, rub it gently with a jewelry polishing cloth. Use a clean cloth, or a clean section of a previously used cloth, so that the gold is not scratched. To avoid creating a pattern, rub it with a polishing cloth in varying straight lines, not in a circular motion.
Machine cleaning:
Sometimes, after the home care cleaning process, your jewelry may still look little dull and tarnished. In this case, your jewelry will need more than just a hand cleaning. Most of the retail jewelers have some type of more abrasive but safe on the jewelry clean equipments such as ultrasonic, ionic, or steam cleaners. Also, they have the experience using these machines as well as the ability to decide which cleaning method is right for the appropriate jewelry and thoroughly clean your gold jewelry for you. The professional ultrasonic machines used in jewelry stores heat the cleaning solution so are more effective than the small ultrasonic machines sold for home use.
Professional polishing:
Professional polishing refers to where your local jeweler uses abrasive papers to remove some of your gold from your jewelry to make it shine again. This cannot be done by home cleaning or cleaning machine. So if you do not want your jewelry's gold to be removed, leading to a lesser value, it is always smart to store your jewelry carefully away from water.
When storing, keep each piece of gold jewelry separate from your other jewelry to avoid scratches. If the jewelry is a delicate gold chain, hanging it from a hook will keep the chain from getting tangled. Or stretch the chain out onto jewelers' anti-tarnish tissue, roll up the tissue, and then place the roll in your jewelry box, lying flat. That will keep the chain from getting knotted and also slow down the chemical process which results in tarnish. You may also want to put it into a plastic bag and squeeze as much air out of it as you can before closing, unless your gold jewelry includes pearls or opals; those gems need exposure to the moisture in the air to maintain their luster.
If your gold jewelry is well cared for and properly stored, you may never have to clean it. That means protecting your gold jewelry from being scratched by other pieces, keeping it in a dry atmosphere by using silica in your jewelry box or putting each piece in an airtight plastic bag, which in addition to keeping the piece dry gives the alloy metals less oxygen to react to, and keeping your gold jewelry away from sulphur producers such as rubber bands. As rubber bands age and break down they release sulphur so wrapping jewelry packages with rubber bands or having rubber bands in your jewelry box will speed up the tarnishing process. Other sulphur producers that you should not use for storing your jewelry are newspapers, clingy plastic wraps, and non-archival cardboard boxes.
As with all jewelry, avoid water at all costs!! Do not wear gold jewelry in a swimming pool or hot tub or when using ammonia or cleaning bleach at home. Bleach, including chlorine, will attack and dissolve the metal so that the more delicate parts, such as connecting rings in a bracelet, will come undone. It's better to not wear gold jewelry in the shower either. The soap can leave a dull finish on the gold that is not easy to remove once it builds up.