Following the nationalisation of all Czech and Slovak glass companies, export relations were put into the hands of two organisations, Skloexport, offices in Liberec and Prague (better known in the West as Glassexport) and Jablonex, (offices in Jablonec,) charged with the export of beads, and costume jewellery manufactured in and around Jablonec nad Nisou.
Confusion arises immediately, when Jablonec-produced ashtrays, carry Glassexport labels.
So it is perhaps easier to say whose glass did not carry Glassexport labels (ie; Bohemia Glass/ Bohemia Crystal, Made in Czechoslovakia.)
NO factory based in the Slovak region carried this label.
For the rest, which did:
Zeleznobrodske Sklo (ZBS)
Karlovarske Sklo Moser,
Sklo Union (all four production units)
Note that it is entirely possible that the Glassexport label may also appear on glass from Skrdlovice, and other small series glass artwork.
Any label attributable to Sklo Union carries the old Inwald crossed Js.
Please, for new-comers sakes, sklo in Czech means glass, so to use the word alone, can be confusing. If anyone means Sklo Union, please use the complete term to refer to that organisation. Not all readers who arrive here will have sufficient knowledge to realise what is being referred to.