Hi, everyone.
I have a customer who have this clock with pictures attached. He wold like the to know the value of this piece. Just some idea and if it have good value, how can he do to certificate it. It is working.

 

Gurzelen was a sister brand of the Omega Watch Company before it was called Omega.
Under the Gurzelen brand the Brandt brothers produced some very fine watches with complications and decoration.

Without detailed photographs and condition assessment its hard to value the watch, and because it's an obscure brand, also hard to find recent past sales for precedence.