Stained glass lamps are frequently used in decor and provide the beauty of artwork with the functionality of a lamp. In the early 20th century, the Tiffany Company introduced a line of stained glass lamps that would later become iconic; several companies quickly reproduced these stained glass lamps. Although a manufacturer may claim it is selling a "Tiffany" lamp, it is often a lamp done in the Tiffany style and not an actual product. There are a few ways to determine whether a Tiffany stained glass lamp is authentic.
Look for the signature on the base of the lamp shade. While not all authentic Tiffany lamps are stamped, the majority will have a small mark on the bottom of the shade that says either "Tiffany Studios" or "Tiffany and Co." If you do not see a mark, this doesn't necessarily mean that the lamp is not authentic, but the chances of it being a reproduction are higher.
Study the base of the lamp. Authentic Tiffany lamps are also marked on the base with the same signature mentioned above. In addition, the bases are made out of copper or bronze and are quite heavy. Later reproductions are commonly made out of resin and may feel very lightweight.
Examine the solder between glass pieces. Real Tiffany lamps are made using copper solder, and reproductions typically use brass or other inferior metals in their solder. Aged copper will look dark greenish-black, while bronze and other metals will typically just appear black. In addition, pay attention to the workmanship of the solder. Tiffany lamps are constructed with strict attention to detail and do not typically show soldering errors or poor workmanship.
Study the design. Tiffany lamps are produced with a variety of detail-heavy designs Common original designs include roses, begonias, dragonflies, peacocks and other flora and fauna. Tiffany glass produced later in the Art Nouveau period may also exhibit what is known as a "mission design" with vibrant color pieces arranged in a southwestern design.
Pay attention to the price. A real Tiffany lamp is considered to be an antique and will be priced much higher than a reproduction. Even at an auction, a Tiffany lamp will sell for several hundred thousand dollars, and according to The Antiques Almanac, some have even reached more than $2.8 million depending on the size and the design on the shade. Reproductions are typically priced from $500 to $5,000. Tiffany "style" lamps will be much cheaper, usually around $100 to $300.