I really don't know much about this shade, never seen another one like it. Can you imagine the mold it must have taken to produce this?? No wonder they weren't common! The condition is remarkable! No chips, no cracks, not even rim fitter roughness! You may see some little marks around the rim fitter, but they're just little indentations for the tightening screws, and even those are perfect!. This shade would dress up just about any lamp & you'll probably never see another one like it!