Go to Atlantis and speak to Dyana, then choose Imbue Stardust and follow the instructions to Imbue Stardust into your gear.

Show Quest Info

Introduction

If the Insignia is diamond, then you can speak to Dyana to imbue the Vitality Stardust LV1 you've received. Each time the attribute gain you get is different, so you need to try more to get the best effect.
Stardust can be produced through Technology and Craft, of which some of the materials come from the Energy Well instance. You can also buy some from Dyana.

NPC Dialog

Now it is Imbue Stardust. After the opening just now, you can use Vitality Stardust LV1 to imbue. Remember, they shall be matched to be imbued.