Thanks Alisa and sorry but we may have a language misunderstanding on my side
did you mean by your comment Fritz Heckert never produced their own glass?
I may have misunderstood what it said in Truitt's then as it says there page 70 - 'Until 1889 Heckert specialised in replicas of 17th and 18th century enamelled glass, decorated in the "Old German" style. In 1889, he acquired his own glass hut and began to produce iridized glass decorated in Art Nouveau style.
' (source Truitt's Collectible Bohemian Glass 1880-1940 - my underlining)