Waagschalen-Ohrringe

The Earring requires the completion of "The Brass Scales" achievement which is the completion of 500 Immortal Flames supply missions. You gain 8 once a day (unlock all of your crafting classes beforehand). Dedicate yourself to getting the Earring and it would take you 63 days (500 / 8).

You would need to first unlock all of your crafting classes. It doesn't matter what level it is; In fact, the lower level they is, the easier the work will be. The idea behind that is that what the Grand Company offers as a supply mission is dependent on what level each crafting class is; the higher level the class, the harder it will be to make the item they want.

If you're at a low level and you don't want to get the materials to make the item, you can actually buy a majority of items from the market board or NPC vendors.

While that is a lot of waiting for +1 spiritbond, it's not a LOT of work and also gets you seals. As the only Earring with Spiritbond (As of 2.28), it can be worth your time.