The Gemology Institute of America reports new problems with lead-glass-filled rubies. Experts at the institute just found a synthetic ruby that had been "improved" with lead glass. A flawless natural ruby is very valuable. Synthetic rubies, made since the early 1900s, cost much less. Lead glass hides flaws but leaves gas-bubble inclusions that can be seen by experts. Beware. "Improved" rubies should sell for much lower prices than natural rubies.
Source: (Actual ruby) AGTA | Agta.org