This is a bracelet, and it's jewelry worn around the arm, but what about jewelry worn around the legs? What do you call it? Is there a particular name for it, or do you just have to call it leg-jewelry?
There are "anklets", which are worn around the ankles.
An anklet, also called ankle chain, ankle bracelet or ankle string, is an ornament worn around the ankle.
Note that "ankle bracelet" in some contexts could be misconstrued as an ankle monitoring device used in law enforcement.
Also, please note that "bracelets" are worn around the wrists. It is clear and natural to say someone wore a bracelet on their arm, but most native speakers will take that to mean it is on that person's wrist. I think the object in your picture would be worn on the upper arm, and therefore is not a bracelet.
There is something called a "bangle". Here is Wikipedia on bangles, for convenience:
But yes, in some cases you would simply say "jewelry". (I suggest not calling it a "jewel") Leg-jewelry is little bit odd, so, personally, I would rearrange the phrase to say (He wore) "jewelry on his leg".