Hello Le Casson,
Regarding my earlier comments, what I meant was simply that if Cathy appreciates the design of the piece and considers it pleasing enough to buy, then this perhaps is a better motivation to purchase than some tentative attribution to a possible designer or maker.
As regards Powolny and (any other named designers who may come into fashion), yes an attribution to him makes a significant difference as to what a piece might sell for but in my experience such attributions are very often made with little or no evidence. It now seems that every tango piece that comes onto the market is a Powolny, when, in fact, they are merely influenced by his designs. Austro-Bohemian glass is one of the most difficult areas to research and many (arguably the majority of) items are sold with incorrect attributions anyway and may make unpredictable prices as a result.
It is perhaps only my personal opinion but I cannot help but feel that the prime appeal of art glass should be aesthetic rather than monetary. Of course, this is practically not the case and many regard items as an investment or buy them only for the purposes of speculation; an arguably valid approach (and one which I have adopted when dealing), but one which fuels a market in which there is a recognition of a few designers at the expense of many more. More who themselves may well have been as competent but didn't for some reason make it into the right books and television programmes to capture the popular imagination.
I would have to check auction records and dealer prices to verify this but if memory serves Chine is far from the most desirable of Loetz decors and hence would not necessarily make a great deal more than a fine example by Kralik. In this specific situation I would simply use quality as a guide, both the tangible quality of execution, i.e. how well made is the piece, how good is the irridescence, and the more intangible qualities of design to decide whether or not to buy it. This, of course, is an entirely personal approach but one which I have found to be very worthwhile.