Instructions
Become familiar with Tiffany shade characteristics: irregular on the shade top and shade bottom; irregular on shade bottom only; geometric; flowered globe; flowered cone and transition to flowers.
Familiarize yourself with popular designs. These included shades with blue dragonflies with purple wings and red, jeweled eyes on a blue-green background; multicolored shades with wisteria, vines and flowers; and floral designs.
Check for original paper labels, and Tiffany signatures pressed into the metal rim of shades. These signatures are usually signed "Tiffany Studios." Notes that these markings are often faked.
Look for a model number on both the lamp base and the shade. Every lamp and shade had a model number, to make the filling of orders easier.
Check for patina, or a darkened, aged look, on the leading between the pieces of glass. Tiffany artists added patina when they made the pieces.
Look for a base large enough to hold oil. The earliest Tiffany lamps burned oil and not electricity. Tiffany bases were made of brass.