Unknown mark on petrified pine brooch

[ValkyrieVixen]

Identifying the stone has been tricky, so far closest seems to be Petrified Pine, likely from Brazil.
I have looked at every foreign mark on the site but none seem close. It tests as a lesser grade silver.

[2209patrick]

[volpone]

Is there any possibility this might be an older Soviet/Russian piece?

[ValkyrieVixen]

Someone suggested that to me but with when I checked Russian marks they seem to be more than one mark, like British silver.

[volpone]

I'm not that familiar with Russian marks, but perhaps the multiple marks would only be applicable to a higher grade silver than that of your brooch?