I hope this is persistence, not pestilence. I have some new evidence that the answer to this query will be found in fairly common mould-blown items in a wide variety of shapes with the characteristic iridescent crackle finish.
Another query on GMB more than seven years ago (link below) describes a closely related vase. That other vase is also round and high-waisted along classical lines, but at 23cm it is slightly taller than the query item of the present thread, and it differs in having only the slightest hint of the flared opening that distinguishes the present query. I believe the suggested connection to Royal Brierley in that other thread is a red herring in the search for the maker there (and here). The other item has a definite crackle surface with some fairly deep fissures, where the RB items offered as comparators are all much more deliberately textured with a surface that is smoother overall. The appearance of the iridescence down inside the fissures of the vase of that topic is a feature quite different from anything to be seen on the RB pieces.
http://www.glassmessages.com/index.php/topic,17152In contrast, the textural features and colouration seen and described in the other vase are also found in the original item of this thread. The one point of difference (apart from the shapes, as noted) is the descriptions given for the base glass material. In the other thread it is called "very dark vivid violet that reads as black", while here it is described as "single dark blue block colour". I'm allowing that this difference is a matter of perception, or perhaps a manufacturing variation, when I contend that the query item of the other thread from 7+ years ago and the query item in this thread are closely related.
Further, I have more direct evidence to connect these two classically round vases to a range of geometric vases as illustrated in Reply #15. A week ago I was in an 'antiques' emporium where I was surprised to find a display by the dealer I referenced in Reply #16. I managed to photograph the three items together in a cabinet (photo below). Importantly, one of these items is round, although in a shape that is different again from the two items in the topics I am connecting. In addition to the similarity of construction and finish of the three items in the photo to each other, they have the same surface as the original items of both topics. This shows that these iridised crackle vases were produced in a variety of shapes.
In the time since my previous post on this topic, another related item in a squat geometric shape has been sold on ebay.au. Thus we now have identified nine items from the same series, in quite different shapes but with a consistent construction and finish. (I'm discounting one of the ebay items that has same iridised crackle finish but on a different colour base material.)
Thus it seems the search for a maker should include the other shapes while keeping focus on the characteristic iridised crackle finish. Many of these items have been found in Australia, but I don't know whether that location is significant or only observer bias on my part. As I said earlier, I had once seen indications of Japanese origin, but annoyingly I cannot recall the details. Other information suggests they date from the 1980s (rather that the 1970s suggested for the query item), but that is mostly hearsay.
Trevor