Probably works for the people who already believe it will work. Placebo is a powerful thing. That said, fidgeting behavior is documented even in certain primate species as a self-soothing behavior. So any piece of jewellery that you learn to associate with self-soothing behaviors (eg: by having something tactile to 'play with', a somewhat abstracted, more intentional form of fidgeting) could help sooth an anxious mind & body. But the jewellery itself doesn't have any anti-anxiety qualities, it's just a cognitive 'anchor' for you to associate with the behavior that provides the soothing effect.
I think that if you believe in it , then it does , not sure there is any absolute facts on the matter , but its a general phycology or phycological action then it is possible that it works , its a state of mind.
I wear a hair tie on my wrist and I play with it when I'm nervous. My friend notices that I do it often and tells me so that I stop fidgeting 🤣. But I think these could work though they are a bit ugly.
Well while I don't have that specific kind of jewelry sometimes when I'm nervous or bored I start playing with my necklace or bracelet if I'm wearing one
Superb Opinion