So what are Boro beads exactly? Borosilicate is a type of glass that is very hard and requires great heat to melt. It was first used in laboratory glass or cookware, such as Pyrex. In the 1980's art glass pioneers starting using Borosilicate to create beads.
During the beadmaking process the boro glass rods can change colors using the chemistry of oxygen and heat. Boro glass beads are usually encased in clear glass to show off the colors better. Because of it's strength it can be used to create more sculptural beads.
Read more from the Art Bead Scene's WikiBeadia: Borosilicate Glass.