Old Metal Flower Spray Brooch?

I bought this really interesting brooch this morning too. It is well worn with a greenish bloom on some of the leaves and stem (copper?). It has beautiful metal roses, and a blue stone, which doesn't really go with the roses! It has a c clasp (I think that's what its called), and the pin has most of the gilding rubbed off. Can anybody suggest age, what it's made of etc.