Those clamshells come in a wide range of colours and there are several different makers. Also red, yellow, pale blue, pale green and clear. They were made until relatively recently, 1970's at least, and probably still made. The main difference between older and newer is the quality and thickness of the metal.
I found the 'blobby' ceiling shades the least attractive, although I do have a nice hemispherical one in thick glass with orangey blobs.