Mystery Green Ceiling Fixture

Hello,

We recently purchased a heritage designated home near Toronto ON, Canada, and found two of these (photo) ceiling lights.  We're interested in finding out more about them!  They are heavy, and appear to be some sort of glass. The house was circa 1920, and we were told they were original to the home.  If anyone has an ideas to put us on the right path, please let us know!

Thanks in advance.