Glass ball from the Vérrerie of Brehat
In its pure form, glass is a transparent, biologically inactive material. Hand blown glassware is popular for its artistry. Some artists in glass include Sidney Waugh, Rene Lalique, Dale Chihuly, and Louis Comfort Tiffany, who were responsible for extraordinary glass objects. The term "crystal glass", derived from rock crystal, has come to denote high-grade colorless glass, often containing lead, and is sometimes applied to any fine hand-blown glass.Photo credit: Chmouel Boudjnah