Old Vintage Brooch Open Back Stones Setting Sterling

Description

Very striking Sterling brooch
I am not sure whether the stones are crystal, glass, or rhinestones.
They are well cut.
The colors are amethyst purple, ruby red, emerald green, sapphire blue, and topaz orange.
They catch the light beautifully, as the backs are open.
They are faceted and many faceted in the back.
The back is gold colored, perhaps gold foil~not quite sure.
The oval on the back is marked sterling.
Good working clasp
It is 2 inches high, and 2+1/2 inches wide.