Malachite, crystal and sterling vtg collar

Great UC. 16” length. Stamped on clasp. Lightweight links with a centerpiece of genuine malachite rectangle surrounded by a halo of pointed clear rhinestones. Some of the crystals are a bit loose but none are missing or chipped. Malachite is in perfect condition. It is glued in rather unattractively but luckily that’s on the back (see photo). I bought this at an antique store and I wish i knew more about this piece. It’s very Hollywood regency Art Deco. Could be from the 50s...or earlier.