A serious collector will have dealings with the many descendants of the 38 caliber movement, like the 0920 QZ. The progeny was divided in SQ, QT, QR and QZ quartzes to keep track of quality and specs. They were the JDM (Japanese Domestic Market) watches made around 1971-75, while the export models were mostly labelled SQ 3003 (QT), SQ 2002 (QR) and SQ 4004 (QZ).
The highest quality and the most expensive of these quartzes were the SQ & QT with tighter specifications - 15s as compared to QR's 20. Only then came the QR and finally (much later in time as well) the QZ. But remember, at this time there were no cheap quartzes so even the "lower grade" QZ was more expensive than the average mechanical watch. This one for instance was priced at 610 Euro in 1975.
We are not done here however, and it does not get any easier as the 38 QZ descendant is introduced finally in 1975 with the 09 series with a 15/20spm specification.
In hindsight, there never was a model year where all these designations existed at the same time, but it is evident that some SQ's are better and more expensive than both the QT and QR. The cheapest QR of course was more expensive than the QZ at introduction but this compares 1971 against 1975 where there has been significant price erosion for quartz watches. The QZ came close to a 1000 Euro in 1971..
That price level had to translate into quality, and yes the Quartz QZ 09 series has Hardlex glass and even a luxurious triple day font function for the 0923. This means that quicksetting it is somewhat more complicated than usual because the date wheel as a matter of course will turn together with the day wheel! This is not a malfunction but a mechanical necessity. After setting the day, one always has to set the date - use the quickset in that order. This gorgeous watch of course is uncomplicated, and very rare to boot,