That is my point exactly, Adam D.
This is becoming rather academic, but ..... :lol:
In simplified terms the color of an object is determined by the interaction of light waves and the individual's eyes who is viewing it. By definition black is the total absorption/adsorption of light waves. Therefore if light can penetrate through a piece of glass, then it can not appear black to the human eye.
I did hold up the light to my black Fenton Big Cookie Jar. It showed a deep purple. But the body of the jar is too thick for light to penetrate and it appears solid opaque black. Together resting on the shelf they both appear to be an opaque black just like the other black Fenton pieces I have on my website. They were all made from the same forumation of black glass.