I love crackle glass beads. They have inner sparkle that catches the light in such a lovely and surprising fashion. The "cracks" in the glass are created by rapidly cooling the beads while they are still hot. The beads are then reheated to smooth the exterior, and make them stronger through out. Colorless Clear Glass About 4mm, some slight variation in size exists. Hole size about 1.1mm Approximately 100 beads per strand. Crackle Glass Beads / Cracked Glass Beads Full Strand measuring just under 16 inches. A bead or two may be misshapen I have two different batches of these that vary slightly in tone. If multiple strands are ordered it is possible they will be from both batches, though I will always match when possible. Measurements are made to the nearest millimeter. Thank you for shopping Smileyboy Beads!