Copper stains the skin — is that normal?

Yes, this is a normal property of copper. In contact with the skin, copper reacts with sweat and skin secretions, forming compounds that can leave a greenish or dark mark on the wrist. How strong it is depends on your individual skin chemistry, humidity and how long you wear the bracelet without a break.

The mark itself washes off easily with soap and water and is not a sign of an allergy or skin damage. If, however, redness, itching or irritation appears, that is a different matter: in that case, stop wearing the bracelet and see a doctor, as it may be a sensitivity to the metal.

To keep the mark to a minimum, you can take the bracelet off before showering, exercising or working with water, and wipe its inner surface with a dry cloth from time to time. Over time the bracelet itself also changes colour — it darkens or develops a patina. This is the natural ageing of copper, not a defect.