Schreiner Brooch - curious about it...

I'm just interested in what this item may be worth. It was donated to our non-profit for a fundraiser and I'd like to make sure we raise as much as possible. On the back it says Schreiner on one part and 713- was etched or scratched on another part. Not missing any stones. Took it to a jeweler, he cleaned it the best he could, there is still some green stuff on the back.