Instructions
Familiarize yourself with the overall appearance of Tiffany Favrile glass. The most instantly striking feature is the iridescence of Favrile. While different techniques exist for iridizing glass, according to World Collectors Net, Favrile iridescence is a result of mixing colors while the glass was still hot. Favrile iridescence is part of the glass itself, not a result of additional surface coatings or overlay. World Collectors Net also asserts that Tiffany himself stated he intended Favrile glass to resemble the wings of butterflies or beetles.
Check for a signature. In an article for WorldArtGlass, art glass appraiser Reyne Haines says that signatures are often the easiest aspects to reproduce, but original Tiffany acid-etched signatures usually appear running left to right beneath the pontil mark, an indention left by the rod used to hold a piece of glass while hot.
Use serial numbers to identify the item. As art glass dealer Philip Chasen explains at his Philip Chasen Antiques blog, Tiffany Studios numbered non-utilitarian pieces; prefix and suffix letters can be indicative of the year of production.
Recognize common colors and motifs. The Antiques Bible reports that Favrile pieces are most often found in shades of gold, green or blue. Furthermore, The Antiques Bible indicates that it is common for gold and green pieces to be translucent, while objects made in blue often include floral designs.
Consult an expert. Reputable dealers are quick to share their experience and expertise.
Become personally acquainted with several verified Favrile pieces. While modern reproductions exist, The Antiques Bible indicates that Tiffany himself destroyed the instructions for making Favrile; no perfect copy, therefore, can exist. Once you have seen, and hopefully even touched, a few true pieces, you'll be more likely to recognize Tiffany's hand-crafted art glass on your own.