They are indeed similar The Royal Watcher! Well spotted. The difference, of course, is that the Powis choker has coloured stones set within the Greek pattern

The choker worn by the Countess of Yarborough appears to be part of a larger, longer jewel. I wonder if it broke into a choker plus bracelets?

For the Devonshire House Ball in 1897 the Countess of Yarborough wore the longer jewel as a bodice ornament on the right hand side of her bodice.



Photos of both sisters in grand jewels seem to be scarce. If instead of jewels this board was devoted to horses, hunting and hounds, we would have plenty of images!