Black onk/Legends

"a simple grip, a curved approach, one inlaid with the bone of the Cartusion whale, pastillion ore or black onk."

- The options given for lightsaber design by Huyang

Black onk was a substance which could be used as an inlay in the handle of lightsabers. When a group of Jedi Padawans visited the Jedi training cruiser Crubcible during the Clone Wars, the Architect droid Huyang who was stationed there informed them that a Black onk infused handle was an option they could select when constructing their own lightsabers.

Behind the scenes
Black onk was first mentioned in 2012 in A Test of Strength, the seventh episode of the fifth season of Star Wars: The Clone Wars, the script for which was written Christian Taylor. The substance was also mentioned in the trivia gallery for the episode on StarWars.com.