I'd be grateful for any help I can get identifying the plates below. The only clue I have is they came together with some other plates which I can identify as Russian (or this could be a red herring). I'm running a small business selling vintage and antique wares in Sweden but noone here recognizes the marks below.
The plates are about 10" diameter. I also have some flatter plates with the same hand-painted marks underneath but the number impressed (e.g. "61" below) is different - therefore I guess this could be some sort of shape identifier.