I have never known them as Mstisov, I have understood that them as being called simply "Borocrystal," Novy Bor Crystalex," Crystalex being the massive complex near Novy Bor which housed Prachen, Exbor, Chribska etc... though later Chribska may have produced the same pattern, I think originally they were made separately under the label "Borocrystal," from Novy Bor Crystalex" but I would be happy to be corrected or have this info amended by anyone with more labels exp. etc...
Robert (bOBA)