Approximately 4-5mm diameter. Sold by the 16" strand. The image below shows the relative size: The necklace above features the Turquoise Magnesite Rectangle bead, Clover Petal Filigree, Ornate Chain, Tibetan Capped Turquoise Beads, and Magnesite Turquoise Cubish Bead Strand. The above necklace uses our Pewter Artistic SW Sun coins, available in 10mm & 20mm. (The 20mm Artistic Sun pewter bead is bigger than the biggest one shown here, but gives you an idea of what you could do with it. We also don't have the Medium sized Sun Coin seen here in stock right now, but the Pewter Shining Swirl Coin is the same size) It also uses Pewter Daisy Spacers, Nunn Design Antique Silver Plated Textured Cable Chain, Pewter Spacer Cube Bead - Flower, Turquoise Magnesite Cubish Bead, Tierracast Silver Plated Scalloped Bead Cap 4mm, Pewter Toggle Clasp Set, Variscite Jasper in 6mm, 8mm, & 10mm and 3mm Turquoise Magnesite.