Goldstone - Victorian sparkle brooches

Here is a material seen in brooches of the later Victorian and Edwardian eras but seemed to fade from popularity by 1920 - it surprises me that Goldstone was not used for longer as it really does sparkle wonderfully. It is actually a type of glass made with thousands of tiny copper inclusions. For some reason I alwasy seem to find goldstone set into Nanny Pins as in the photo below: