Onyx necklace
From Emps-World Wiki
Onyx necklace is made by using a Gold bar on a furnace whilst also having a Necklace mould and an Onyx in the inventory. Doing so requires a Crafting level of 82 and gives 480 experience when made.
The Onyx necklace can be enchanted into a Berserker necklace by using lvl-6 enchant from the Normal spellbook on it.