A couple of years ago I bought this piece from a seller on etsy who irradiates all kinds of glass, at that time he did not mention it, so i questioned if he irradiated this particular piece. he stated that he may have as he had been doing so since either the 70s or 80s. I told him that he ought to mention that in his descriptions, i don't know whether or not he heeded that advice. I have here photograph of when i first got the piece and put it on a side pin out front, and then a photograph a couple of years later on the same pin. never taking the insulator off of the pin the next photograph is what it looks like as of this posting...