Sterling Silver Plated over copper. Marked S925 (S925 and 925P both stand for Sterling silver Plated. The S usually stands for Plated over Copper). These are great earrings for those who have jobs where wearing larger earrings are not allowed (I sold about 20 to 2 different police departments to the women police. They loved them as they fit the dress code. the earrings are 3.55-4mm wide and about 1/2 inch in diameter.