then we shall defer to your first hand experience David

All I can say is that if you blow up both of Chris' images showing the 'depression' they each appear to show very different surface finishes - which seems odd.
The first appears not to show any linear scratches, and has what looks like a frost effect, whereas the later pic does show what Chris describes as grinding marks 'running in several different directions'.
I'm sure this piece isn't remotely Victorian, but at a quick glance it reminded me of some epergne cones where the colour graduates in delicate pastel tones.
Anyway, I'm rambling and contributing nothing of value I'm sure.
