Large numbers of glass-filled ruby are entering the marketplace, according to a pair of articles featured in back-to-back issues of Gemworld International’s Gem Market News. (“Lead Glass Filled/Repaired Rubies,” Gem Market News, July/August 2006; “The Process and Identification of Filled Rubies With Lead Glass,” Gem Market News, September/October 2006.)

The author, Vincent Pardieu, director of the Asian Institute of Gemological Sciences in Bangkok, Thailand, noted the material’s popularity as an inexpensive ruby alternative. He quotes one ruby treater saying, “Imagine how much a 20 ct. heat-treated ruby would cost, and compare that to one of our stones of equal beauty. We are so [much less expensive].”

In just two months during the winter of 2004/05, AIGS examined more than 200 filled rubies. The largest weighed 97 cts. Because so much material has entered the market, the enhancement is creating significant amounts of salable rubies from inexpensive, highly fractured, unattractive red corundum.

Identification is relatively easy, says Pardieu. “Microscopic observation is in most cases enough for the experienced gemologist.”