Returning

When a dragon reaches an age of 800 years, they are culturally expected to perform the Returning. The dragon forfeits its soul back to the world, becoming once again their natural essence. In this, the cycle of dragons continues.
  The Returning leaves no body and no bones. They are disintegrated into the essence of the dragon. What is left is a Dragon's Remembrance, a gem formed of the memory of the dragon.
  Some dragons flee from the Returning, refusing to give back for any number of reasons. Sometimes these dissenters escape Kai'Diin and live their ancient lives in other lands.
  Dragons who either rule on the The Twin Throne or founded a house are allowed to forego the Returning, instead living forever.