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.
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.
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.