The so-called nickel allergy refers that, when nickel-contained jewelry is in prolonged
contact with human skin, nickel would be dissolved out under the erosion of sweat and release nickel ions, these ions would be further penetrated under epidermis, react with some proteins and cause allergic reactions such as erythema, pimples, eczema, itching, inflammation and even
ulcerating, which would seriously influence human body appearance and health.