The back side is threaded, like a cap... and there seems to be a purply, crystally, glassy, edge to it. Found at a h omesite, 1920's. My impression is that it is brass, and painted white, like an old appliance
Thanks for looking
I like the idea of a lampshade finial, but the crystal-like feature is curious to me. Perhaps the pics don't show it, but there is a purple crystal showing through the paint
Toilet hold down nut. You'd have one on each side of the toilet. They attached to long threaded bolts and had a washer under the nut. If you tightened it down too much, you'd crack the toilet! Too little and your toilet would wobble!
I think Qsilver has nailed it... In fact, after I signed off last nite, I was looking up at my bathroom light, found myself staring at the nut that holds on the ceiling/globe lamp. Thanks guys for your ideas and opinions, stay tuned for another mystery....BWD