It is difficult to identify because it was often unmarked.The famous iridescent glass by Tiffany Studios was usually marked "Favrile."Steuben Glass Works marked its glass "Aurene" or "Steuben."Union Glass Co. used the name "Kew Blas" for its golden iridescent glass.Quezal glass by Martin Bach was almost always unmarked.Glass made by Victor Durand was occasionally marked with the word "Durand" and the letter "V."Imperial Glass Co. and the Fenton Art Glass Co. made iridescent glass marked with a paper label that washed off, leaving an unmarked piece.For many years, the glass made by Loetz in Austria confused American collectors.Loetz manufactured pieces in unusual iridescent patterns and uncommon shapes.
Although Tiffany glass is still considered the most desirable, the iridescent pieces by Loetz are almost as popular with today's collectors.
Look carefully at pieces of golden glass. Steuben made a glass that looked more like brass than gold. Loetz items often have a silver sheen. Slight differences like these can help identify the maker.