Many jewelry suppliers mistakenly advertise with "nickel-free" jewelry. The admixture of nickel has the positive property of making the metal more resistant and protecting it from rust. Even "surgical steel" can contain up to 14% nickel. This is fine as long as the specified limits according to the "REACH" (Registration, Evaluation, Authorization and Restriction of Chemicals) EU chemical regulation are respected. All my jewelry has been tested in the laboratory for the above chemicals and are harmless to your health and therefore "nickel safe".
A big advantage is also that gold and silver are two high-quality anallergic precious metals in contrast to base metals and he is therefore harmless to allergy sufferers.