Vintage-look Necklace

Great vintage-look necklace. Another estate find and I do not know much about the necklace. The pendant appears to be a green slab cut stone with a marbleized/abalone look set in an ornate gold frame with tiny pink/green/clear stones or crystals. Measures 1" x 2" The necklace links may be jade with tiny gold ball spacers. Measures 18" length with a lobster claw clasp and a 1.5" chain link extender. No visible hallmarks. One tiny clear stone on the top bale is missing but not really noticeable unless you look closely. Please note the last picture showing the above-mentioned. Pre-owned and very gently worn with very minor signs of wear. Good condition. (see above)