Here is a quick and easy guide on how to upgrade your Ring, Necklace, Charm and Moon.
The location of the NPCs that will help you ugprade your items are located in the following areas.
Addon Keep (Human)
Wirtz Keep (Akkan)
Let's break this down in subgroups:
Jewelry Upgrade (Ring and Necklace)
Materials: Jewelry Ang Pau & Golden Jewelry Ang Pau
There is also quest on how to obtain a Jewelry Ang Pau
The Jewel Enhancer NPCs will assist you in upgrading your rings and necklaces