Thank you for the analysis!
Response to Garf:
It is not a secret. So the origin of the star remains unknown. My family inherited it from my great-great grandmother who was not by any means a royal. She was commoner in central/eastern Serbia at the time (Very beginning of 20th century). We assume she found it somewhere or it fell off of someone like that. We have no supporting documentation, no box, anything else. Since than, star has been in our family for 3-4 generations as our "little treasure". That's everyting we know about the origin (we know nothing about how it landed in my family's hands since my family was never a part of any royalty.)
Hopefully we will continue researching together.