These beautiful Murano Mod beads are made in the bollicino technique referred to as "Tiny Bubbles." Each bead has randomly placed bubbles inside, best seen by looking from the side. This bead is grey steel Murano glass over .925 sterling silver with a sterling silver insert. The size of the hole is about 4mm and the bead is about 13-14mm in diameter. This bead is compatible with other popular European-Style modular charm bracelet systems. Made in Italy.