Like many other Czechoslovakian entities of this time, Crystalex has a complex history. It was formed in 1974 as the umbrella organization for plants in Novy Bor, Kemenov Senov, Harrachov, and Chribska. The plants included what had been, and would return to being, the Moser and Egermann plants. The combine produced a wide range of glass, The name Crystalex is on some labels, mainly art glass made at one of the Novy Bor plants. Designers included, Pavel Hlava, the first chair of the Board of Directors of Crystalex, Matura, Jelinek, Suhajek, Oliva and Wunsch. This info comes mainly from Helmut Ricke's book with a little from Langhamer.
I've used the rule of thumb looking at Czech glass that if a piece I like isn't Skrdlovice, then it must be Crystalex (or some variation).
Posting the pieces you have labeled Crystalex would help in determining who designed them, as well as bringing some enjoyment to collectors like me.