I my ruby glass filled?

[userangl28212003]

I recently bought a lovely antique style ruby and diamond ring, which I fell in love with. I was said it was a natural ruby and only 1/2 a carat, but that is as far as it goes for details. I am no expert, but I try to do a lot of research and study what inclusions look like and i could tell that it was not synthetic at least, I did expected it to be heated though. The next day under bright light i noticed some flashes of blue in kind of circular form only in the bottom left area of the ruby. I suspect that it could be led glass filling, and I wanted to know what people thought that have more experience in rubies than me. I am planning to replace the ruby because of my suspicions. Thank
you