If you’ve ever gone on a trip and purchased what you thought was a beautiful silver piece of jewelry, only to come home and find that it turns your skin green after a few wears, you know that some jewelry can react with your skin. It’s true that some metals darken over time and that others can even turn your skin green. The good news is that stainless steel is not one of them.

Costume jewelry, sterling silver or fake gold can sometimes leave a green mark on your skin after wear. Though you might assume this is an infection or an allergic reaction, this is actually the result of a chemical reaction taking place on your skin. Sterling silver, fake gold and various materials used in costume jewelry are often mixed with copper and other metals, which contain compounds that react with the acid in your sweat to form green-colored salts. Because sweat is part of the equation, it’s likely that the green mark on your skin is more obvious on warmer days.

Stainless steel jewelry should not turn green itself and will not cause your skin to turn green. While it does contain traces of nickel, it is not released from the steel because it is very well integrated into the material. For those who may be sensitive to metals and who want to get their ears pierced, doctors may recommend using nickel-free studs and a stainless steel needle.

To prevent your skin from turning green, paint your piece of jewelry with clear nail polish so the reaction between the skin and metal cannot take place. In addition, keep your fingers dry and try to avoid wearing the offending jewelry to the gym and on really warm days when you’ll likely sweat. If is does turn green, use a little bit of soap and elbow grease to remove it.

Some people may experience true allergies to metal jewelry. In addition to staining, symptoms to watch out for include red, irritated and itchy skin. The most common jewelry-related allergy is to nickel, which is very often mixed with other metals such as gold.

If you experience skin irritations, redness and other allergy symptoms, try sticking to sterling silver and at least 14-carat gold or hypoallergenic jewelry which is less likely to offend. Some soaps, lotions and makeup can react with nickel to cause these allergic reactions on the skin, so try using different cosmetics to see if there is a change.