316L steel, or surgical steel as it is also called, is the material that most of our jewelry is made of. It contains about 17% chromium, 12% nickel and 2.2% molybdenum, but it is so tightly bound in the metal that less than 0.1 millionths of a gram of nickel is released per cm2 and week. This is so little that 316L meets the EU directive for products that come into close and prolonged contact with the skin. The limit value is 0.5 millionths of a gram/cm2/week. "Ordinary" nickel allergy sufferers usually handle the steel perfectly well, but if you are very sensitive or worried, you can choose titanium instead.
Titanium is completely nickel-free and is suitable for sensitive and very allergic people. It is half the weight of steel, and is one of the five substances that are best accepted by the body. It is not actually the titanium itself that is so good for the body, but the layer of titanium oxide that forms on the surface. The oxide layer also acts as a barrier against other substances in the titanium leaking into the body. If the titanium oxide surface is worn away, a new layer is formed immediately.