Every piece of jewelry needs a setting. So if you have a chain, you need a setting to go with it for discovery.
So for necklaces/amulets, it’s a chain + setting + jewel.
For earrings, it’s hook + setting + jewel.
For rings, it’s band + setting + jewel.
Filigrees are used for discovering upgrades. Filigree + jewel for discovery.
Once you have passed a certain point in a particular tier, you can use the upgraded jewel to make jewelry.
Hope this helps.