A hundred years ago glass doorknobs were pretty common.
Some were fancy crystal, and some were fancy cut glass, but most were cast or molded glass, sometimes in colors.
I have some glass knobs that are a light lavender, not made that way, but because ultraviolet light would affect old clear glass that way over time.
But you ain't seen no knob, like this knob, anywhere near... uh, anywhere.
Round, smooth, and a reflection of the room.
Close.
The reflection is of the room on the other side of the door, great for bathrooms.
I'm not sure if it works both ways, or not, but placement would be a challenge either way.
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