925 sterling silver
Sterling tarnishes; that’s normal, and it polishes back. A soft cloth after wear and a dry drawer between wearings keep it bright. The platinum finish over the silver is a plating, and every plating is finite — it goes first where the piece is handled most, not evenly all over, and any jeweller can redo it. Reach for a dry cloth rather than a silver polish: polish lifts the finish faster than it lifts the tarnish. The slow patina is the honest life of a real metal, not a flaw.