Kyber Crystals are sacrosanct to the Jedi. They power their light sabers. Finding them is a right of passage. Fantastically, we use crystals in similar fashions.
The Kyber crystal was first introduce into Star Wars lore in the Legends book Splinter of the Minds Eye, published in 1978. In the book, Luke and Leia are told of the Kaiburr Crystal by an old woman who claimed it contained the ability to magnify and focus the power of the Force-sensitive.
Over the years, the myth of Kyber crystals has continued to develop. Through various episodes of Star Wars: The Clone Wars (The Gathering, Crystal Crisis on Utapau) and Star Wars Rebels (Path of the Jedi) and books like Ahsoka and Rogue One: Catalyst, we have learned more and more about their place in the Star Wars universe and their relationship with the Jedi. It shows a color based on the nature (or manipulation) of the crystal and its relationship to the Jedi.
But they’re not real. Almost.
It turns out that there are practical uses for crystals that aren’t unlike the lore of the Kyber Crystal. The most accessible is that of the Ruby Laser.
The Ruby Laser was developed in the 1960’s as a medium for producing a laser. How they work is fairly straight forward in operation, but hard to explain. In short, the electrons in a ruby crystal is excited such that it emits light. Here’s a reasonably good explanation:
It’s actually not unlike the theory behind light sabers. Except, you know how the Force effects them.
But these objects are eminently practical. Lasers are used in every day objects. The most common is perhaps a bar code scanner.
I’ve talked about the difficulty with the technical concept of the Light Saber. All other elements not withstanding, it’s the power source that is the limiting factor. In Ruby lasers, the crystal is the medium for producing a uniform light source. It is not a power source and the benefit of exciting electrons, though awesome, is limited.