Our sculpted transparent gray with black mosaic hollow mouth blown Murano glass bead in the smaller approximately 20mm(+/- 2mm) size and in a flat coin, penny shape. The beads are blown and then after they have cooled are hand worked to grind the ridges in them. Sometimes the grinding goes through the glass, this is not a defect just how they are made and does not weaken the bead. They are little pieces are art no two alike.