What jewellery? You may be thinking of gemstones and you can find one at the bus crash site (in the bus, at the back) or for completing the chicken catcher quest, or if you've found those two you can ask the fortune teller next to mia's construction for a hint on another(at the cost of 10 gold).
I haven't played for awhile so forgive me if i dont remember there being any jewellery items in the game on the top of head when i think of it.