Grey Agate 833 silver hallmark help please

I’ve tried very hard to do my due diligence with this one but without much luck so I’d love some help please.
The chain and pendant and clasp all have the same hallmarks but they are very tiny so apologies for the photos, they are as clear as I can get.
One looks like a splodge (head?) with 833 (835?) underneath and one that is best described as looking like a treble clef musical note (lines with a circle in the centre)
Google keeps pulling me to Dutch but then mentions a bunch of European countries that it could be!
The spring ring clasp looks quite an old design and the mount for the agate(?) looks hand chased.
Thankyou for any suggestions as to age or origin!

 

I agree with google.

In that case it isn't Dutch, we use symbols for finenesses, not numbers.
My guess would be Austria.

 

Ok, Thankyou, I’ll research Austrian marks