Hi Tony - many thanks for taking the photos of that vase. It certainly isn't one that is frequently found, and it has a superb iridescence, and in fact is pretty scarce.
The pattern is known as "Columbia" and it is Classic Carnival - made by Imperial. The colour is smoke
- and it really is a gorgeous example of it.
In another thread recently, I mentioned the colour smoke. It's not always easy to get a good photo of it, that shows the smoky iridescence on the clear glass base. Your photo is excellent and shows the clear base glass very well indeed (on the foot). http://www.glassmessages.com/index.php/topic,5874.0.html
Thanks Tony, for sharing those pics of a lovely, scarce vase.