While much has been written about glass filled ruby and its sudden surge of presence in the marketplace and ease of identification, little has been written regarding the instability of this material. About a year ago, at the Tucson trade show, glass filled ruby started to appear in quantity. Although we know of some being sold without disclosure, most of the ruby we encountered was disclosed as such. Identification is simple, looking for the telltale "flash effect" under low magnification. This is the same principle as glass filled diamonds where a flash of color is observed as the stone is rocked while examining under magnification.
One of the key identification features of lead glass-filled rubies is the flash effect. This sample shows a strong blue flash in brightfield illumination, and the orange flash is visible in darkfield. Photomicrograph by Shane F. McClure, magnified 10x © GIA
At first we were not concerned since identification was easy. The price was so low that these did not seem to be worth a second look. However, now, these rubies are beginning to show up after the filler has been damaged from simple jewelry work. The American Gem Trade Association (AGTA) operates a Gem Testing Center in New York. Dr. Lore Kiefert, Director of the lab has encountered several damaged rubies submitted for identification and evaluation regarding cause of damage. Unfortunately, when these rubies are exposed to heat, the filler is greatly damaged. In fact, common household products like bleach and ammonia can also damage the filler. The images here show how bad these stones can look after damage.
Now, according to Dr. Kiefert, the labs are encountering more of these rubies that appear to be a lead glass mass with fragments of rubies inside. The accompanying photo shows the high reflect lead glass with lower reflective ruby when viewed in transmitted light.
Glass filled rubies showing severe damage to the filler due to heat exposure. Courtesy AGTA GTC.
When asked about potential health risks, since this filler is lead-based, Dr. Kiefert stated, "I think that this is a health issue for manufacturers who work with this all the time. If lead paint already makes such a fuss, these people would be exposed to the fumes and that should be even worse."
Lead glass-filled ruby showing large lead-based mass in transmitted light. Courtesy AGTA GTC.
To learn more about Glass Filled Ruby, or to find a jeweler who can properly evaluate a ruby you have purchased in the past, please contact the AJA.
