Lampwork is the term for making glass beads using a torch. This type of work has been done for thousands of years, though today we have special torches, hand tools, and glass rods. This is a very short answer to a complex type of artwork!
I make most of my pieces from soft or soda lime glass which is specifically made for torching. It was formulated for making beads but with a lot of practice and patience, it can be sculpted.
Borosilicate, or boro, is considered hard glass. It can also be used for torchwork, though it isn't as delicate as soft glass. If you've seen people making clear glass animals and flowers at festivals, odds are they were using borosilicate glass.
While the glass is being manipulated in the flame it is constantly cooling and reheating. This causes a lot of internal stress. If the bead isn't cooled carefully, the bead is likely to crack and break.
Well-made beads go directly from the torch to a kiln that is set just under 1000 degrees Farenheit, just below the melting point of the glass. The beads sit in the kiln long enough for the glass to become the same temperature all the way to the core, removing the stress. The kiln then temperature drops slowly so that the bead isn't stressed again.
Yes, glass can be broken if dropped on a hard surface. The annealing process definitely makes glass beads less likely to break, but like all good artwork, glass requires care.
Glass cleaners like Windex work perfectly. Warm, soapy water and a soft toothbrush can also do a good job. If you are cleaning a finished piece of jewelry, you'll need to consider the type of metal used since some cleaners can damage fine metals.
Mass-produced beads are made in factory settings with little if any creativity included. They are usually common designs and the focus is on productivity, not workmanship. Often, craft store beads still have bead release in the hole which can be a health hazard.
Artisan glass beads are made by people who love the process of working with molten glass. The equipment and supplies can be rather expensive. Taking classes to learn advanced techniques is pricey and often requires travel. Learning to make quality beads takes years of study with lots of mistakes and experimentation along the way.
Consider that you are purchasing the time, talent, and genuine care that the artist has invested in your one-of-a-kind glass piece.