Hi Michel, lovely azur "pineapple" vase by Vizner. Azur is one of my favourite colourways and as you say late 60's early 70's it was very popular as a colourway and can be an indicator of production date to some extent. Jindrich may have more to say on use of Azur at Skrdlovice, having discussed this era of design with Mr Vizner himself on several occasions and having seen later Beranek Glass production at first hand etc... In the 50's there are some colourways that were very short lived. Rosalin or pure salmon pink seems to have been almost entirely 55 and 56 for example. More research has to be done in this area but patterns do form over time. One interesting thing about ebay is how reliable the secondary market is regarding production and historic exports. It is quite clear from this that one of the major importers of Skrdlovice c. 1955-1963 was Canada. Also, regarding rare items or small production runs, quite clearly some items appear regularly, indicating quite large scale production runs and some quite rarely or perhaps once, probably indicating smaller runs. The pattern books do give some indication of initial runs, sometimes specifying in the opening pages "up to a thousand pieces" this is quite common in the fifties. However, this is only true for the initial run and in following years they sometimes made many more. So, in the late 60's and early 70's patterns where it says 1200 pieces I would not at all take it as gospel since some of these are the most common patterns we find. However, some of these, because they are rarely seen, almost certainly were made in 1200 and no more. Beyond this, it is hard to be more precise without trying to talk to someone like Svoboda and going through the books and his memories page by page (which may well be worth doing). In the mean time, I attach some recent purchases, not very good photos, I'm afraid, I am experimenting with a new set up, that needs organising. One piece is a 1953 Labut-Svicen (swan-candle holder) by Veliskova. This colourway seems to have been 53-58. This seems quite a scarce thing which is a surprise, I would have thought a swan, with a free candle holder, would have been a best seller!!
The other piece is an Emanuel Beranek piece with four holes, weighing about 2KG and from memory is 1959, showing how far away from Sarpaneva orchid type vases his own experiments and designs took him. Ricke and Digrin seem very uncharitable in suggesting his efforts were just to make more apertures than Sarpaneva, after all, Emanuel Beranek was a glass designer as well as master blower and this piece does not look anything like a vase from Scandinavia.