These dark blue ones (images 1, 2) from the work of New York architect Gil Schafer cast a rich hue onto the door when light passes through them. And a variety of colors are to be found in this collection (image 3) from This Old House.
Glass doorknobs came into ubiquity in the United States during World War I. Prior to that, doorknobs were made of cast iron, bronze, or brass. But during the war, these metals grew scarce and turned doorknob production toward cast and cut glass, which was quite common into the 1950's.