Stone Size: 3.0mm earrings exceed all F.D.A / E.C requirements. Earrings are sealed and sterilized in individual packages. Studs are white surgical stainless steel. Earrings backs are grooved friction post for secure fastening. Ear piercing studs are not returnable if packaging has been altered. Sold per dozen. Universal piercing studs should only be used with the brand universal system piercing instrument.