Shraki

A kyber crystal, simply known as a kyber and described as a lightsaber crystal or the living crystal, was a rare, Force-attuned crystal that grew naturally and was found on various planets across the galaxy. Known in ancient times as a kaiburr crystal, it was used by both the Jedi and the Sith in the construction of their lightsabers. As part of their Jedi training, younglings were sent to the Crystal Cave of the ice planet of Ilum to seek their own lightsaber crystals. The crystal’s mix of unique luster was called “the water of the kyber” by the Jedi.[2] There were also larger, rarer crystals of great power and that, according to legends, were used at the heart of ancient superweapons by the Sith.

Through an unspecified process involving being placed in a furnace and hammering, kyber crystals could be tempered to match with the nature of multiple individuals multiple times, beside bonding with just one for life. When these tempered crystals are placed within a weapon such as a lightsaber, its color will change within moments upon being picked up by a new wielder.