I know this thread is a bit ancient now, but it seemed the best place to post an update, as it's the top result for "Opaline Florence":
A while ago, I emailed the Vetreria Di Borgonovo website
, sent them a link
to my website showing lots of "V.B. Opaline Florence" items, and asked if they made them. It seems they didn't, this was their response:"This is hand made and most probably it has been manufactured somewhere in Empoli area.
Empoli is a province in Tuscany - Italy
Regards and good luck
Vetreria di Borgonovo SpA"
(The company is based in Borgonovo, not Empoli, although it's not a million miles away).
Since then, I've recently come across a couple of items with labels which read "Veritable Opaline Florence", so I'm assuming the V.B. is just short for "Veritable"? See pics below.
It looks like Veritable Opaline Florence is just the style or range of glass, so the jury is still out on who made these. My best guess
would be Stelvia, who made similar glass and have similar labels. Would love to know what others think, or if any new info has since been found?
(http://www.20thcenturyglass.com/images/items/glass_labels/glasslabels_murano16.jpg) (http://www.20thcenturyglass.com/images/items/glass_labels/glasslabels_murano50.jpg) (http://www.20thcenturyglass.com/images/items/glass_labels/glasslabels_murano26.jpg)