http://www.youtube.com/watch?v=p8hfswXRyFwThe Video link above has a couple of interesting points:
1) At 50 secs, click Pause, then double click to step through frame by frame, bringing into view two blue and "brown" vases in the lower right corner of the image. I suspect the "brown" could be aventurine. Both vases have small loop handles at the neck and the one to the right seems to have the rounded loop shape as seen in the vase in this thread and other threads, including the Fossilfly one mentioned earlier.
2) At 1 minute 20 secs listen to the commentary about the modern art glass, where it is said, "... manufactured in our own facility in China ..."
Ok, these snippets are not conclusive proof of anything, and the blue-brown vases do not appear to have the obvious "pull ups" within the decor as in the other vases discussed. But taken as a whole I think there is enough there to make a good case for these mystery vases to be from the Dale Tiffany company and quite possibly made in China.
Perhaps an email to the company would settle the matter?