Each bead is individually handmade and no two are exactly alike. Lampwork beads are made on a metal rod called a mandrel. The mandrel is coated with a white powder that will allow the bead to be taken off the rod when the bead is finished. Molten glass is wound around the mandrel and the mandrel is placed over a flame (originally the flame of a gas lamp). The bead is shaped and carefully decorated.
It is then annealed (allowed to cool evenly and slowly) to add durability. No two lampwork beads are exactly alike.
If you'd like to see how lampwork glass beads are made, I think you'll enjoy this video I borrrowed from YouTube.