Question about Star Piercing Stud earrings silver with square crystal black

The "Sterling silver stud earrings with black square crystal (Sterling silver)" by Star Piercing are nickel-safe. The material used is sterling silver, which is an alloy of 92.5% silver and other metals, and generally contains a very low percentage of nickel, if any at all. Sterling silver is considered a biocompatible material and suitable for those with nickel allergies.