Unlike the Jedi, who wielded various colored lightsabers, the Sith all carried red lightsabers. It was a symbol of their unity and unwavering dedication to the Dark side of the Force.
In both canon and Legends, Jedi will sometimes use red-bladed lightsabers in emergencies where they're missing their lightsabers and a Sith weapon is the only one available. Some Jedi are explicitly shown using red lightsabers in Legends, however.
Construction. In the construction of a Sith lightsaber, individuals partook in a process known as bleeding. By ways of the Force, they would pour negative emotions such as rage, hate, fear and pain into kyber crystals. The process would result in the crystals gaining a distinctive crimson or red hue.
Generally speaking, red lightsabers are typically used by Sith or Dark Side users, while blue lightsabers are often wielded by Jedi or Light Side users. However, certain Jedi and Sith have used other colors, such as yellow and purple.
Red lightsabers are the weakest, according to a Star Wars study conducted at the University of Leicester regarding lightsaber colors. Decades of Star Wars lore has dictated that the red lightsabers favored by The Sith offered greater offensive capabilities than the softer colors favored by The Jedi.
Purple itself is considered the most powerful lightsaber color in the Star Wars galaxy. Very few Jedi have ever wielded a lightsaber of this color. The only two people known to have wielded a purple lightsaber are Mace Windu and Darth Revan in the past.
Purple. Only one person in canon wields a purple blade: the Jedi Council's Mace Windu. He uses it to decapitate the deadly bounty hunter Jango Fett in Attack of the Clones and to deflect Darth Sidious' Force Lightning with it -- disfiguring his face -- in Revenge of the Sith.
Ahsoka Tano, the former Jedi Padawan who aided in the rebellion against the Galactic Empire, is acknowledged as the sole possessor of the white lightsaber.
In the Sith Empire, as time progressed pure-blooded Sith were steadily bred out, resulting in only a few pure-blooded Sith left in the Sith Empire by the time of the Great Hyperspace War (5000 BBY). By 44 ABY, the true Sith species in the Empire were believed to have gone extinct due to the interbreeding process.
The weapon had a kyber crystal at its heart, and emitted a yellow-colored plasma blade when ignited. The emitter matrix on Rey's weapon featured a rotating gear-like mechanism, which caused the emitter of the lightsaber to open up and allow the plasma blade through.
While blue, red, and green lightsaber crystals are the most common colors in the Star Wars universe, purple lightsabers are less often seen, and these exceedingly rare crystals were used by few duelists throughout history. Jedi are most commonly seen with the purple lightsaber.
As a result, those who wielded a purple lightsaber had a strong connection to both the Light and Dark sides of the Force. Purple color is a combination of good and evil, the majority of Star wars characters were too loyal to one side or the other to wield a weapon of this genius and stealth.
Vader eventually killed the Jedi Master and retrieved his green-bladed lightsaber. He headed to Mustafar, where he bled the saber's crystal, turning it from green to red.
It's possible that Rey adopted the yellow-bladed lightsaber (or perhaps the kyber crystal conjured a yellow blade based on the changes within its wielder) in honor of those emotionally detached sentinels tasked with guarding the Jedi Order.
Kylo Ren, the dark side persona of Ben Solo, altered his lightsaber to suit his new preferences as a dark Force-user, changing his Jedi weapon into a red-bladed Sith lightsaber.
At the end of the film, Rey returns to Luke's home on Tatooine, where she buries Luke and Leia's lightsabers, then reveals her own—decked out with a golden-yellow blade, a hilt that looks like it might've been crafted from her staff, and a cigarette-lighter-looking switch that turns it on.
Lightsabers with ghostfire crystal cores also generated almost no sound and produced illusory afterimages of the blade that followed the motions of the wielder, the most curious effect of all which disguised the true position of the blade while also disorienting foes.
The cost of rebellion was a high one for the proud planet, turning the sight of Mandalorian armor into a rarity in the years following the fall of the Empire. In the first-season finale, Moff Gideon, former officer of the Empire, emerges from the wreckage of his fallen TIE fighter. And he wields the Darksaber...
Leia Organa's lightsaber was a blue-bladed lightsaber powered by a kyber crystal in the core of the hilt. It was silver and copper in color and featured mother-of-pearl inlays. Organa's weapon was considered a work of art, having an elegant symmetry with silver and gold hues that evoke to her upbringing on Alderaan.
Constructed by the ancient Mandalorian Jedi Tarre Viszla, the only true black-bladed lightsaber has become a symbol of strength and leadership among the strictly principled Mandalorian people.
Luke Skywalker's lightsaber was changed from blue to green when they were filming because it was difficult to see. This became apparent during act one of Return of the Jedi when the battle on Jabba the Hutt's sail barge was shot during the day. The blue lightsaber blended in with the clear blue sky.
While there are many one-of-a-kind lightsabers in the Star Wars universe, there is only one with the history and legend of the Darksaber, which was created by the first Mandalorian Jedi named Tarre Vizsla.
While countless fell to his Force skills, most were killed by Vader's crimson lightsaber which became one of the most feared weapons in the galaxy.