glass (n.)
Old English glæs "glass, a glass vessel," from Proto-Germanic *glasam (cognates: Old Saxon glas, Middle Dutch and Dutch glas, German Glas, Old Norse gler "glass, looking glass," Danish glar), from PIE *ghel- (2) "to shine," with derivatives referring to bright materials and gold (cognates: Latin glaber "smooth, bald," Old Church Slavonic gladuku, Lithuanian glodus "smooth"), with derivatives referring to colors and bright materials, a word that is the root of widespread words for gray, blue, green, and yellow (such as Old English glær "amber," Latin glaesum "amber," Old Irish glass "green, blue, gray," Welsh glas "blue;" see glass). Sense of "drinking glass" is early 13c.

The glass slipper in "Cinderella" is perhaps an error by Charles Perrault, translating in 1697, mistaking Old French voir "ermine, fur" for verre "glass." In other versions of the tale it is a fur slipper. The proverb about people in glass houses throwing stones is attested by 1779, but earlier forms go back to 17c.:
Who hath glass-windows of his own must take heed how he throws stones at his house. ... He that hath a body made of glass must not throw stones at another. [John Ray, "Handbook of Proverbs," 1670]
glass (v.)
late 14c., "to fit with glass;" 1570s, "to cover with glass," from glass (n.). Related: Glassed; glassing.