Pre- WW 1 (1918): “V. Kohlert’s Söhne Graslitz”. The Bohemian border region belonged to the Austrian Empire. Most inhabitants, also the Graslitz instrument makers like Kohlert, Püchner, Keilwerth, and many others, were German
1918- 38: “V.Kohlert’s Söhne, Graslitz, Czecho-Slovakia”. The region was part of the new Czecho-Slovak Republic. According to New Langwill they were among the largest firms of WWI makers in Bohemia with workforce of 400 in 1929 and a 23- piece orchestra.
After Nazi Germany had, by the Munich treaty of 1938, taken over the German- Bohemian border region, it was: “Graslitz, Sudetengau”.
After WW 2, till about 1948, when the Germans (“Sudetendeutsche”) were expropriated and expelled by the Czechoslovak state: “V.Kohlerta Synobe Kraslice” . The former Kohlert workshops were then taken over by the state owned Amati company.
At Winnenden near Stuttgart, South Germany, they started their business again. The instruments were then stamped “Kohlert & Co. Winnenden” They had to give up, as far as I know, about 1980.