Silver Stud Earrings with Grey Button Shaped River Pearl 6-6.5 mmPearl Stud Earrings These sterling silver stud earrings are set with grey, cultured river pearls. The pearls have a classic button shape and measure between 6mm and 6. 5mm in diameter. Crafted from sterling silver, an alloy containing 92. 5% pure silver, the settings provide a bright and durable finish. Each stud is held securely in place with a matching butterfly back.