14 karat white gold amethyst bead necklace with French cut diamonds

This is a vintage piece, I'm having trouble really narrowing down the age because it definitely has an Art Deco feel to it, but some of the smaller stones are early modern which leads me to believe that this may be from the 40s Deco resurgence.

First I will discuss the necklace portion of the piece. At 18" the amethyst beads that make up the necklace are 8 mm wide. They are an excellent condition and a beautiful bluish purple. They're also very consistent in color which makes my heart go pitter patter. The clasp is made by someone having drilled thread into the amethyst bead and putting a screw in roundel of 14k white gold and diamonds. The pendant is actually removable which means it could easily be put on a string of pearls as well. It has a carved amethyst cameo (I'm not sure if that's the correct term) that measures 20.3 x 15.3 mm and is surrounded by 14 karat yellow gold. There are two antique French cut diamonds and early modern round diamonds in the platinum portion of the pendant. The pendant portion is an 1 3/4". It is 42.8 g