Hi---the rim has definitely not been ground---I've looked using a 10x lens.
In this instance the camera did lie.
The rims of my Caithness vases are flat and clearly defined. And you can see( on the inside edge ) minute flakes left by the grinder.
The rim of my vase isn't nearly as flat, in fact, in places it's quite curved. And there's no sign of flaking anywhere. It might have been fire-polished?
I'll try and describe it's exterior surface as best I can.
The film( for want of a better word, I'll call it that ) starts at the top of the rim--approx mid-way.
There's a very faint join line here. It's here that you get some iridescence/rainbow colours ( only really noticeable under a lens)
This film has been applied to cover the whole external surface of the vase ( other than the base ie the bit it sits on)
The film finishes about 1-2mm from the bottom of the vase. Where it finishes there's another very faint line, albeit wavy in places.
So ,the only part that hasn't been covered is essentially the part that the vase sits on.
The base, which is clear, is fairly dished. In it's centre there is possibly the vestige of a Pontil scar---a small hardly noticeable swelling.
I hope all this makes sense.