Pretty sure they date to around the 1930s - give a decade either way. The line inscribed inside the scroll motif appears in early 20th century cinnabar, but never after WWII.

And it doesn't appear to be moisture that decomposes them so much as heat. And not much heat - body temperature alone seems enough to impart a shiny gloss.

Genuine urushi tree-sap lacquer has the curious feature that it requires a warm, humid environment for the sap to polymerize into a tough, resistant coating. I wonder if they added too much oil or wax to the sap, and it never cured properly? Oil or wax might account for the tendency of the stuff to melt under heat.

I've assembled a modest suite of photographs of auction offerings over the past few years that are making me wonder if these necklaces and bracelets were the products of one Chinese workshop. They all feature

-brass dangles,
-stone nuggets and small round beads either plain or carved with a shou character of turquoise, carnelian agate, jade, some sort of lapis or dyed jasper,
-splashy folk-art style cloisonne beads in an immediately recognizable design
-Chinese filigree work
-an odd assortment of what appear to be European? findings and chain, none of which resemble those connected with the Miriam Haskell atelier.

So I wonder, did these pre-date the Haskell designs and inspire them, or vice versa?