Glass is seemingly everywhere, but not all glass is created equal—and just how unequal can be a bit of a mystery. What antique glassware brands should you be aware of? And how can you identify what kind of antique or vintage glass it is? Thomas Webb Art Nouveau Pair of Glass Vases $1,144 at 1stDibsTiffany StudiosIn the U.S., Tiffany Studios, founded in the U.S. by the son of the founder of Tiffany & Company, Louis Comfort Tiffany, produced a type of glass called Favrile glass, meaning handmade. Most are signed, but there are plenty of pieces by Tiffany contemporaries that produced glass in the same style—and achieved critical acclaim and commercial success— and signed with marks that are hard to identify.