These carafes (jugs/flasks/decanters?) are 9" high, weigh approx. 700g, and are in a deep cobalt glass with lovely purple hues. Random bubbles apparent when held up to the light. Not the prettiest polished pontil, not quite round and also off-centre. There are some faint concentric circles around the pontil mark. There are slight "ridges" on the body - these can be felt more than seen, although I have managed to capture them in a picture. Quite thickly made - one piece has had, literally, a lump out of it, without causing any damage to the surrounding glass. It is helpful to have a pair as the very slight variations - such as the wonky rim on one - make it clear they are handmade.
I was absolutely convinced I had seen a thread here recently with a piece (one of Anne's maybe) with the same prunt, which was a maker's mark rather than a decorative or practical feature. I thought I had made a mental note to look out for this prunt. However, I have failed completely to find a single other piece with a prunt with this pattern. The closest prunt pattern I could identify is the "rosette prunt".
So far I have searched for carafe/jug/flask/decanter in all possible combinations with glass/blue/cobalt. I've even just searched for "glass prunt". The colour reminded me of my Hadeland cobalt decanter, so I looked at Hadeland and most of the usual Scandinavian suspects.
I wondered if there used to be a silver collar, or silver mount with handle, as the neck between the shoulders and where it flares for the spout is very straight and there is a hint of a line (this is really hard to explain!), but it could just be from the way it was made.
A search of the board failed to locate the thread with the same prunt…..but I am spending so much time looking at glass these days that I'm even dreaming about it, so maybe I dreamt it!