No, the vase isn't Iridescent, wish it was!
Also has a pontil mark underneath, so it was not polished. Another thing I found interesting is that the top of the clear glass was not polished off either. It was left rough, and the "crown leaf" motif added to it. I do think it was done at the same time and isn't a "marriage." That is what makes me think it is a much older piece too.
Oh, and on the glass, it is just really really dirty, from years of being inside the store. I am cleaning it now and looks really clear.
For a signature, I really havent found one. Would you think it is a stamp-like signature I should be looking for? I have been trying to feel with my fingers in case it is etched or stamped, but nothing so far.