The green color that you see on stainless steel parts is chromium oxide (Cr2O3). It forms when there is too much oxygen and/or moisture. Oxidation is not a manufacturing defect or fault.
316L Stainless Steel has excellent corrosion resistance, but it is not impervious to rust. Chloride is an excellent rust cause with a little damp air moisture.
Which metals are used in alloys? Copper and nickel are metals used in alloys, and both are known to discolor skin.
Some factors that cause jewelry to oxidize and turn black or discolor :
- An individual’s body acid. Your jewelry may be at a higher or earlier risk if you enjoy drinking or eating foods that are high in acid like; coffee, wine, fruit juices, oranges, tomatoes, vinegar, pickles, etc. Read more at the high acidic foods list.
- Prescription drugs. Certain medications like anti-depressants, sulfa drugs, some antibiotics or even multivitamins can interact with or change a person’s body chemistry.
- Cleaning products and chemicals. Direct contact with bleach, ammonia, acid, alcohol, chlorine, etc. will cause a chemical reaction to the metals of jewelry.
- Menopause. Woman in menopause can experience body chemistry and hormonal changes that make oxidation more possible while their body adjusting.
- Extremely moist skin. Some people can have physiological or metabolic states that stimulate excess moisture and perspiration (sweat) even without purposeful exercising. Especially moist skin can interact with the 7.5% metals with a green skin staining.
Will everyone experience skin discoloration? Unfortunately, some people’s biological responses and genetic chemistry predispose them to skin discoloration. For example, two friends can buy matching friendship bracelets, and one of them will experience skin discoloration, while the other shows no signs.