Whats maker could it be?

[Kirils]

Could this be Otto Schneider? I've taken a look at his work and I didnt find any Jugendstil peaces.

[silverfan]

the mark of Otto Schneider, Berlin is an S. I suppose the mark behind the 800 to be the eagle of Bruckmann, Heilbronn. Perhaps you see more when you clean this mark with an old tooth brush.
Regards silverfan

[Bahner]

Hello, agree with Silverfan, most likely the Bruckmann eagle. Schneider is probably the retailing jeweler. Regards, Bahner

[Kirils]

Thank you silverfan and Bahner for your help. I've cleaned the mark and it does look like Bruckmann eagle.