It has some copper peaking out around the glass. There is discoloration and rippling in some of it. The only marking I could find was a plate etched with SPECTRUM installed to the inside. It was hanging in a home built in the 1850's. The owners didn't want it in the remodel and were going to throw it away. I asked if I could purchase it instead and they gave it to me. I wish I could know what it is for sure. The blue dragonflies seem to be rare especially in this color combination.
Approx 21inch across and with the taper I'd guess 14inches of depth/height