What is it? Schreiner?

This unsigned brooch measures 2" by 2". The front looks a lot like a Schreiner with its reverse prong set rhinestones. But the back doesn't look quite right.

The brooch was part of my mother's collection. She had a number of Schreiners, but the reverse of this one looks different from the others. She didn't have another with shiny reverse gold metal or with the ring shape.

Thanks for your help identifying the designer of this brooch!