dark-and-light-rise:

The initial brief, as per the script, was to design a two-part pendant that would’ve split between Rose and her sister. Story-wise, that developed into two identical pendants – one for each sister – but the “yin and yang” aspect led the design. Set decorator Richard Roberts suggested some Celtic reference that influenced one design, which quickly became Rian’s favorite, and that design stuck. – Matthew Savage, Prop Concept Designer

– A Rose in Bloom, The Art of Star Wars: The Last Jedi