c1900s gold portrait painted brooch

Im guessing this is made in the early 1900s based on the brass pin back it has.
it has an unusual amount of detail in the painting and I dont see very many with gold leaf like this on it. However, Im not sure where to look to learn more about these so I came here.
When I removed the brooch from the pin back, there was either a 10 or an 11 stamped into the porcelin . I dont know if that helps or not.
I was hoping someone would be able to either show me where to look online to learn more.. maybe it was made by a common artist? or, if there are different search terms I could use to learn about it, that would be great too. I dont know how much its worth, so if anyone has a good guess on that aspect, that would be helpful too
Thank you!