Before the events of color of a lightsaber’s blade if they modify or refurbish the weapon. Anakin did this to Ahsoka’s lightsabers, turning their blades from green and green-yellow to blue. Considering the extensive repairs that Rey made to Anakin’s old weapon, some might wonder why its blade didn’t become yellow like Rey’s personal weapon.
Lightsaber lore in the colors for lightsabers, but the crystals can become purple, yellow, or orange on rare occasions. Just as the Force and the Jedi represent nature and balance, the dark side and its adherents, like the Sith and Knights of Ren, represent corruption, imbalance, and the unnatural. Dark side s must “bleed” crystals to make them work for them, turning them red in the process.
After Ahsoka Tano left the Jedi Order, Anakin recovered and refurbished her lightsabers, turning their blades blue in the process. Decades later, the now-deceased Anakin’s lightsaber was split in half shortly before the Battle of Crait. Thanks to healing techniques she learned from ancient Jedi texts, Rey mended Anakin’s Kyber crystal and repaired the hilt, restoring it to working condition. The Kyber crystal and (and subsequently, the blade) remained blue, however. Rey would later construct yellow-bladed lightsaber. There are several possible reasons why she didn’t change Anakin’s lightsaber blade color. Rey and the Kyber may not have bonded, Rey’s healing method might have been different from Anakin’s modifications, and perhaps Leia had some influence on the healing process and the crystal.
When Anakin refurbished Ahsoka’s lightsabers, he did more than simply fix the wear and tear they sustained during Ahsoka’s brief time as a fugitive of the Republic. According to Dave Filoni, Anakin made a series of modifications to the weapons. In doing so the Kyber crystals bonded with Anakin, changing their frequency and thus their color. Rey had no personal connection to Anakin, having been born long after his death. Rey might not have been able to alter their frequency because of this.
Another important detail is that Star Wars Rebels, Ezra Bridger’s first crystal became blue upon bonding with him, but his second Kyber was green. This indicated that a Force can create working Kyber crystals with more than one color.
Anakin’s Kyber may have simply not bonded with Rey at all. Rey’s healing process might have restored the legendary lightsaber to working condition, but without creating a bond with Anakin’s crystal. Unlike Anakin’s modifications to Ahsoka’s lightsabers, Rey might not have wanted to leave her mark on the historical weapon, so she made sure it was as close to its original condition as possible, including the blade color. When Rey’s Jedi journey was complete in Star Wars: The Rise of Skywalker, she finally created a lightsaber of her own, this time with a blade whose distinctive yellow hue matched her unorthodox path to knighthood.
