Glass filled corundum has been around the market for a long time now. Cheap and unusable corundum with cracks are filled with lead glass to improve its color and clarity. It is basically a clarity enhancement treatment where a gemstone is treated to appear marketable and more beautiful. In a way it is a very good thing as it provides the market with affordable beautiful stones, which actually makes it possible for a common man to obtain a beautiful Ruby at a reasonable price. Treatment in itself is not deceit, as long as the costumer is provided with the correct information about the stone and the price is related to the real quality of the stone. So the matter here to be considered is its disclosure and the durability concern it pose.
The idea was to develop a glass compound suitable to repair fissures in rubies. In fact it is not a new treatment as similar treatment was applied with diamond. Yehuda diamonds which were clarity enhanced by filling it with high RI glass gave similar results. The efficiency of the treatment is such that a single large fracture in an otherwise clean ruby could be made to disappear to the unaided eye exactly as filled fractures in diamond and emeralds. However it is more stable than emerald treatment where only oil is impregnated. Glass filler may be unstable at elevated temperatures and to chemical agent, so special care should be taken when repairing jewelry items set with glass filled corundum. So, when such a stone is sold a proper disclosure should be made to avoid this problem.