Ok, so I'm sure you've all browsed through lampwork bead listings on Etsy or Ebay. I'm sure you've seen listings that say "annealed in a computer controlled kiln." What does that mean?
As glass is heated, manipulated, and cooled, strain occurs in the bead. It doesn't matter if you use the same rod of glass or how fast you work, or even if you try to slowly cool the bead using the torch. That stress is inevitable. That is why annealing is absolutely necessary. If the bead is not annealed, sooner or later that stress will catch up, and the bead will likely crack.
It is important to heat the glass until it reaches a stress-relief point, or annealing tempurature, and hold it until all the stress has left the bead. After being held at the proper tempurature, the beads are slowly and evenly cooled, so no more stress occurs until they are room tempurature. This process takes several hours. I usually let my kiln run overnight.
Many imported beads are not properly annealed and can break and chip easily. When I leave my own beads on the desk, I drop them all the time, but I've haven't had one break on me yet because they're properly annealed. They're like rocks! When you are shopping for handmade artisan beads, ask if they are annealed. It will ensure a long happy bead life.