These examples of a decorative lamp show another facet of colored glass design. Here I have used clear glass with a few colored inclusions. Now, such an " opaque " glass is not necessarily suitable for large-scale use in a luminaire - unless you sandblast it.
So in this case, I frosted the glass on the underside before processing it over a large area. Your glass dealer should be able to provide you with this service. The photo is a bit deceiving - in reality the pyramids are completely illuminated.