What is the name of the iridescent glass developed by Louis Comfort Tiffany?

The iridescent glass developed by Louis Comfort Tiffany was Favrile glass.

Favrile began as a trade name for art glass made at Tiffany Furnaces, the glassmaking operation associated with Tiffany. Its shimmering surface was intended to resemble the natural iridescence seen on ancient Roman and Islamic glass recovered from the ground. Tiffany and his glassmaking team adapted that inspiration into a modern decorative material.

The effect came from combining colored glass with metallic compounds, producing a lustrous, color-shifting surface rather than ordinary transparent glass. Favrile was used for blown vases, bowls, lamp shades, mosaics, stained-glass windows, and jewelry. Arthur J. Nash was an important glassmaker in developing the production technique, although the glass is identified with Tiffany’s artistic direction and company.

A common mix-up is confusing Favrile with Tiffany’s broader category of art glass. Tiffany glass includes many varieties, such as opalescent and drapery glass; Favrile specifically points to the iridescent type. Tiffany patented the Favrile name in 1894, and the material received major attention at the 1900 Paris Exposition.