Hi markus -
just a few things to clarify:
1) This is a Russian silver lover´s forum -
not a "no charge appraisal office"!!!
2) 99% of all enamel cloisonné was made in and around Moscow - very, very little in St. Petersburg, by some famous firms
3) Your Karelian birch/enamel cloisonné objects are nice but "folcloristic" objects - made by many different firms - always in or around Moscow
4) The different Russian Artels were cooperatives, which worked in the highest quality levels possible - they made no simple and cheap articles (in the sense of makmanshift!)
5) Your photo - I see a dot left behind the head - take a loupe and have a look ...

6) Guarantee stamp for Moscow

7) Guarantee stamp for St. Petersburg

I repeat: your objects are nice and in this top condition today not often seen (the wood is often broken, missing etc.) - be happy and enjoy!
Regards
Zolotnik