picking holes in my semantics??

I agree that the phraseology was less than good, but hoped the meaning might none the less be apparent. I was trying to make a distinction between C18 Bristol blue - so called for the reasons you have indicated - and C20 blue coloured glass which had nothing to do with Bristol (although we still call it Bristol blue).
My distinction was, as much as anything else, to simply separate old and new blue glass, and I chose the word 'reproduction' carelessly.
I agree that the name refers to a particular kind of deep blue, although it will always have an association with Bristol. Why is Prussian blue so called??
My apologies to all those who may well be scratching their heads in confusion.

In my opinion, the size of the gilt decorated grape and vine on this piece suggests it's C20 Continental.

P.S. My wife's left Bristol................. and gone to live in Hull

now watch that get rubbed out.