1940s Brooch ?

This is a gold tone brooch, Im not sure of the materials it is made of ?
It has the word "sterling" on the back, but no other markings etc. Several weeks ago I purchased this one from a local shop .
Not sure of the possible year this was make? It has no discoloration to the amber stones. It appears to be in good condition. I do know that it is old, but how old, Im not sure ?

Let me know if you can help identify the era of this brooch and the maker ? I think it is rather pretty, I like the amber color stones !