These all photograph really differently depending on light as can be seen with my bowl.
I'm often wrong on my hunches (understatement)

but I really think this is Webb Corbett.
If you look at your base picture here
http://www.glassmessages.com/index.php?action=dlattach;topic=61823.0;attach=185415;imageand my picture attached to this post, there is no way that they are not from the same place. (Unless someone was giving out ready made mixtures of those colours and powders).
The colours in the base shot of your bowl are all found in the amethyst and blue interior Webb Corbett pieces as they are in my bowl.
Your base shot also shows the little teeny bubbles.
I think it's just that your vase body picked up less of the marvered colour bits.
This base shot of a signed vase also contains those colours and effect of your bowl base, but in addition contains little bright purply blue specks as well. These can be seen in the candlesticks that Brucebanner posted on another thread.
http://www.glassmessages.com/index.php?action=dlattach;topic=63514.0;attach=196091;imageMy bowl's not arrived yet but I will post pics when it does.