Here is a vintage Mid Century Modern closed light shade in frosted glass with a clear glass block style bottom side. It would generally be mounted on a wall with the clear side down, most likely on an enclosed porch, bathroom, or over a kitchen sink. It measures 5-5/8" high with the neck and lip at the bottom and 4-5/8" wide, with a neck diameter of 3-1/4" at its widest; this must fit inside your fixture.

It has good color with no cracks, chips, fleabites, or breaks. There are flecks in the painted frosting at the neck, which would be inside the fixture. See last photo.

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