If your jewelry is looking a little dull, it’s probably time for a good cleaning. Air and water oxidize metals, causing them to turn yellow or even black, so regular cleaning is a must. But it’s not a one-size-fits-all process; different materials need to be handled differently. From porous organic gemstones like coral and pearls to scratch-prone metals such as silver, jewel cleaner comes in many formulations, from liquid sprays and wipes to machine polishers and creams.

The best jewel cleaner for your jewelry depends on what kind you have, so make sure you read the label carefully. Most products have a list of recommended use and cautions that detail which types of metal and stones are safe for treatment. Some only work on one or the other, and others — such as the Connoisseurs Dazzle Drops Advanced, described below — are designed to clean all kinds of jewelry at the same time, including precious gems.

For gold and silver pieces, try soaking them for about 10 minutes in a solution of 1/2 cup clear ammonia diluted with 1 cup warm water. Then, brush them gently with an old toothbrush and rinse. This method is not suitable for opals, emeralds or other soft, porous gemstones, and it may also damage enamel or plated jewelry.