Ring Mottles as Somewhat Stolen From Uroboros

Ring Mottle Opalescent Sheet Glass- a unique art glass style of glass slowly dying off  in popularity... shamefully

Originally discovered by the Tiffany Studios in the early 20th century, Ring Mottles are a special effect of localized, heat-treated opacification and crystal-growth dynamics. Louis Comfort Tiffany was searching for glass containing realistic natural effects to express his representational imagery with minimal use of painting. He couldn't have been happier than when he saw the first accidentally formed Ring Mottles, and he found myriad uses for them!

After the closure of the Tiffany Furnaces in Corona, New York in 1931, Ring Mottles were thought to be lost to the stained glass industry. In the mid '70s, Uroboros' founder Eric Lovell successfully reproduced them and brought them back into the stained glass marketplace. Since then, like in Tiffany's day, Ring Mottles have been used for realistic-looking shadows, sunspots on leaves or ground, or to create small background repeats of larger foreground pieces. Cut lines that follow individual rings can produce the best shadowed effect.  An example is the use of green mottled areas in the background areas behind individually cut green leaves.
Another is the use of flower-colored mottles in the background of larger flower pieces. In large pieces, mottles may be used in groups or cut in half to break up the circular images and achieve a single band through each piece.
Ring Mottles are also used in contemporary works when nonlinear or abstract color patterns are desired. Typical locations might be in border row pieces, background areas around a beveled interior, or in flat panels in lamps.
Bullseye stopped producing mottles several years ago, pretty well leaving Uroboros to carry the torch alone.
And carry it they seem to do with great effect. We carry as much of their mottles as possible, as well as the rest of their line, and are glad to show it off when you come in. We also have several reference books such as Alastair Duncan's Lamps of Tiffany that can show you to great effect why you might want to consider ring mottles in a project.