I took the vase to some natural light and looked for that purple to show better. I agree that it's just the opalescence making it look that way. I can only get a purple cast to it at certain angles. It also has a flat, unpolished base with no pontil mark.
That Collector's Weekly link is very helpful and I think that's sending me in the right direction. Thank you so much for your help and kind comments for a newbie like me!