Hello! Thank you for your question!
Below is an explanation from Dr. Robert Brill, Research Scientist Emeritus of The Corning Museum of Glass:
Usually, selenium is used in glassmaking to produce either pink transparent glasses or (in the form of cadmium selenide) ruby-colored glasses. The ruby glasses were used -- and probably still are used -- for signal lamps.
Selenium was probably not used much before the closing years of the 19th century or after the turn of the 20th century, perhaps about 1910. By the 1930s (or perhaps a little earlier) it was commonly used in decorative pressed glasses. I always think of selenium in connection with the sort of pink candy dishes or the like given away at movie theatres in the 1930s.
Because of its pink color, it was used as a decolorizer. The pink color would offset the aqua color caused by iron impurities.
Online Research Guide
You might also be interested in the Rakow Library's research guide on color.
Please do not hesitate to contact us with your glass-related questions in the future.
