Empire griffin slag glass lamp

I believe this is an Empire. Can anyone confirm? I apologize the pics weren't horizontal when I uploaded them...? Did other makers use a ridge to hold the glass in? Brass and iron. Circle base piece magnetized, upright piece and shade non mag. Glass holding ridges and harp are iron. Cord comes out of the base between base pieces, has flat flexible prongs holding glass, ridge along each piece of glass at bottom that glass sits in. Beige and pink glass which appear original and appropriately aged. Marked on base as S1091 or 1601S. Not sure if the S comes first or last or if it's a 6 or 9. All the letters and numbers, in this case, can be read either way (upside down or not). I've seen other lamps with these griffins and oval in different configurations however nothing definitively identified Empire. Thank you.