Stainless steel

"surgical" stainless steel is a popular jewelry material

First of all, there is no technical term "surgical" stainless steel. If anything, this is a marketing term. However, "implant" grade stainless steel (common grades nomenclatures include "316L", "316LVM", "ASTM F138", or "ISO standard 5832-1" and "ISO standard 6892") is quite real.

Stainless steel contains nickel, which will leach out of the jewelry over time, and will cause allergic reactions in some people.