Hello Emmi.
I have one of these in Ruby, and the rim is rounded, blobby, and all over the place, as seems to be the norm with the photographs of other ones I've seen. But the rim of the MG one is distinctly flat and angular on top (but still fire-polished) like it was pushed against a marver when being formed.
Edit:
Rim Close-Up (http://i18.photobucket.com/albums/b108/pinkspoons/knobbly.jpg)
If the flattening is intentional, might it have been designed as a lamp base? I see no evidence that it ever had any fitting on it, so it's just idle speculation....
It seems that 'squidge' is a hard quality to capture on camera! I'm not sure I've managed it.
Profile (http://i18.photobucket.com/albums/b108/pinkspoons/2-9.jpg)
Rim Close-up (http://i18.photobucket.com/albums/b108/pinkspoons/knobbly2.jpg)
Top View (http://i18.photobucket.com/albums/b108/pinkspoons/4-4.jpg)
Actually, I suspect this Ruby one is the odd man out - as it's incredibly thickly cased in clear glass, making the walls probably an inch thick in places, and some of the 'knobbles' are clear crystal. You can see the thickness on the top view, especially at bottom-left (it's equally thick all the way around, it was just impossible to angle the shot to show this in one image). It's 500g heavier than the green vase and weighs in at just under 3kg.