Beautiful vintage necklace with the large glass cabochons being open backed, the setting of the back of the pendant has the trademarks of House of Schreiner jewerly, as is also seen in vintage Austrian pieces too, I would guess the necklace to either be Schreiner or Austria.  It is gorgeous made up of huge art glass with foil and opal red fire to it, all rhinestones are present, measures about 19″L, pendant measures just over 1 1/2″W by 1 3/4″H.