I have an art nouveau style oil lamp with a ceramic body and with a single mark on the side, which I cannot identify. Seems like initials, but I was unable to find anything related to the company.
The lamp factory was founded in 1841, then in 1878 the owner founded a pottery factory in Znaim, which was mainly responsible for the ceramic bodies for their lamps. But they had a different logo and mark, RDZ, which is not to be found on this lamp.
