How do 750 gold earrings make white-collar workers black?

It's the reaction of gold and hand cream. The black sleeves of the gold bracelet are the reaction of gold and hand cream. Remember that gold cannot be put together with toiletries, including cosmetics. If the above situation is excluded, then your bracelet may be fake. The gold bracelet has blackened the wrist, which can basically be seen as fake, because gold will not fade. When wearing gold bracelets, you should pay attention to avoid contact with chemicals such as perfume and hair gel, and take them off when cleaning or swimming, so as not to affect the surface color.