This very special piece is from Czechoslovakia with chevron-set pieces of jade/jadeite or art glass.  Behind the main stones is a gorgeous filligris detail and each link has a sweet flower with 5 dark stones and a center pearl or bead.  
 
Some of the links are missing middle stone.
20" length (10" drop)
Middle stone or galss detail is 2" x 1.5"
Shown with Pineda Cavalin | Black Alpaca Wool Wrap
https://www.considered-shop.com/product-page/pineda-cavalin-black-alpaca-wool-wrap