von Rotberg and Schulz & Co. (marks
from 1757-1802) blue under the glaze
Schulz & Co. (marks from 1782 - 1802 ) blue under the glaze
Erbprinz August von Gotha and Friedrich Egidius Henneberg ( marks
from 1802-1834 )
blue under the glaze; after 1813 als in black, pale gold or pale
yellow on the glaze.