An enhancement jewel served as a spherical element utilized within a high-resolution projection system, functioning alongside a focusing lens. Back in 23 ABY, the Wookiee Jedi trainee named Lowbacca employed one of these jewels, which he had scavenged from discarded parts left behind by Rebel technicians inside the Great Temple situated on the moon of Yavin 4, and repurposed it as a crystal for use in his lightsaber.
This particular component initially appeared in the pages of Young Jedi Knights: Lightsabers, a book aimed at young readers that came out in 1998. It was penned by Kevin J. Anderson together with Rebecca Moesta and represented the fourth installment within the Star Wars: Young Jedi Knights series.