Plus two necklaces featuring those oval cloisonne pendants/beads with findings that seem identical to those used in the box clasp necklaces.

My current hypothesis is that someone in China made charm necklaces featuring Chinese stones, cinnabar, cloisonne and silver filigree in the style used for Chinese necklaces but adapted for foreign tourists. [see blog post link - http://www.beadiste.com/2015/12/puzzling-evidence-deco-chinese-charm.html]

Perhaps some of these foreign tourists - Miriam Haskell, for a prime example -
bought a supply of similar Chinese components, and made a raft of necklaces, bracelets, and brooches using them.

Helen Burton evidently made a trip to Rhode Island in the late 1930s (will have to re-find this source) and sold a bunch of things. Maybe whatever the East Coast costume jewelry workshop responsible for this jewelry - if it was indeed a workshop there instead of China or Europe - stocked up from her?

And when WWII intervened to cut supply lines to Asia, substituted wood and "Bakelite" and glass components to continue this "Chinese charms" look.