In the beginning of the Star Wars franchise no one gave much thought to what powered a Jedi’s lightsaber or what fueled the Death Star and made it such a devastating force. In fact kyber crystals weren’t known as such until The Clone Wars series brought the idea into the mainstream. The fans knew about them long before this thanks to the books but the series managed to expand upon them and detail just why kyber crystals were so important and why they were so prized by so many. In a sense these crystals are the perfect energy conduit since they can channel and redirect massive amounts of energy and, if they’re pure and not cracked or otherwise tainted, they can be highly useful as weapons of mass destruction or of a more personal nature. But as much as has been discovered and revealed about kyber crystals they’re still something of a mystery to those that handle them and to the fans.
The potential for the crystals is a big reason why people will pay a king’s ransom or kill for them, since they can be one of the most devastating weapons known to the galaxy.
The Death Star was powered by kyber crystals.
If you’ll remember Rogue One: A Star Wars Story, then you should recall that the Death Star was in fact powered by massive kyber crystals that had been mined and taken by the Empire so as to fuel this enormous, moon-sized weapon. Each crystal was massive and the force it could generate was so incredibly powerful that it stood to reason that just one of them would be enough to destroy a city when utilized in such a manner. But the Death Star used multiple crystals to focus its awesome, destructive capability, which is why it was able to wipe the city of Jedha away so easily under low power and was then able to completely obliterate Alderaan when Grand Moff Tarkin was in the mood to make an example. The only real failing, besides the controversial exhaust port, was that the single shot used under full power would drain the system and require a full day for it to recharge. But to think that the Death Star could be used for surgical strikes or as a method of utter annihilation is just flat out scary.
The crystals take on their color due to the user’s connection to the Force.
Of course the main use of the kyber crystals in the Star Wars franchise has to do with the lightsabers wielded by the Jedi and the Sith. Their weapons are one of the most iconic parts of the story and are seen to be one of the most popular aspects. But a kyber crystal would often change color in response to the Jedi wielding it, using their connection to the Force to change different colors as it’s been explained. For a Sith however the reason behind the red coloring is simple. This is a matter of how the Sith used the Force and the violent acts that they were known for when it came to their ideologies. The kyber crystals were essentially neutral though were Force-sensitive and would take on the traits of the user. The crystals would therefore ‘bleed’ when they were used by a Sith, which was what caused the red color and gave the blade such a fearsome appearance. The hatred, lust for power, and other negative feelings that the Sith felt so continuously throughout their lives were what made their kyber crystals glow a deep and dangerous crimson, as their deeds spoke of danger, hatred, and despair that caused the crystals to reflect those powerful emotions.
There have been synthetic kyber crystals.
The possibility of creating a synthetic kyber crystal has been around for some time. In fact Luke Skywalker made his own crystal at one point, but it was far less powerful and didn’t work quite as well. The synthetic crystals can be made to be stable and to work, but they’re nowhere near as powerful as the real thing and thus are not quite as capable of holding up under the strain that a true kyber could handle. The power output that a true kyber crystal is capable of would shatter a synthetic pretty easily and possibly damage the casing it was in as well as the wielder. While some in the stories have tried to perfect this method there’s just no competing with a real kyber crystal.
On another note a lot of people have asked about different lightsaber designs, Kylo Ren’s in particular. Not only did his blade have a crosspiece unlike other sabers, but it crackled and looked rather unstable as well. This is because Kylo Ren’s kyber crystal was cracked and as a result the emissions were simply too powerful and unstable and required the extra ports to allow the energy to be dispersed in other directions. The blade itself crackles as it does because of the fault in the crystal, but it still works quite well as you’ve seen if you watched the movies.