The thunderstone necklace is made by using a gold bar, a thunderstone and a necklace mould on a furnace. It requires a Crafting level of 108 to make and provides 188 experience when made. Since the necklace is untradeable, the only way to obtain it would be to make it from a thunderstone. At 115 Magic, the oceanstone necklace can be enchanted into an absorbing necklace by using the Enchant Level 8 Jewellery spell.