I've had this for awhile and it is a family heirloom of sorts. I am not sure what the stone is and what the metal is - silver, white gold, or platinum. No makers marks on it. Looks like from the 20s.
I'd go with brass and glass too. There are markings on the pin shaft but it's doubtful they are anything but a makers mark. There is some damage on the stone surround. Better pictures would help.