Some years later I have come across reference to Jos.Schuster & Co when researching the "Cristallerie de Turn" mentioned in A Study of Loetz Cut Glass Production by Dr. K. M. Hasselbach : "As there was not enough capacity for cutting available at Klostermuehle, Loetz established in 1925 another cutting place at Unterreichenstein (Rejštejn ) together with Jos. Schuster&Co [Lnen, page 60] to satisfy the demand for traditionally bohemian cut glass and marked it mainly to Europe under 'Cristallerie de Turn'." The '[Lnen, page 60]' refers to Jitka Lněničková : 'Johann Loetz Glas aus dem Boehmerwald 1824-1939'.
The Cristallerie de Turn is also mentioned in an article on perfume bottles again by Jitka Lněničková in Pressglas-Korrespondenz Nr. 06/2000 : "Welt der Duftbehälter" : "In einigen lokalen Raffinerien wurde auch Toiletten-Glas verziert: Albrecht & Co. - Košt‘any, Pestner & Co. - Košt‘any, Cristallerie de Turn - Trnovany usw. Auch bei der Firma F. Welz ist die Produktion von Puder-Dosen belegt."
Not saying that the label is Jos.Schuster & Co but is certainly over the border in Czechoslovakia.