Identify lamps in Tiffany's Favrile group by finding the metal tag on the inside of the shade. Look on the rim and in the metal work that holds the glass. Look for the initials L.C.T or the word "Favrile," "Tiffany Studies N.Y." or "Louis C. Tiffany Favrile."
Examine the bronze base of the lamp for a stamp that reads, "Tiffany," along with a unique model number. Search for the stamp on the bottom or sides of the lamp base or look inside the lamp shade.
Look for an original paper label that reads "Tiffany and Company." Use caution when examining the label as original labels will be very delicate. Find the paper labels on the bottom of the lamp base.