In Rogue One there is a scene when Empire is plundering the Temple of the Kyber on Jedha.
From Rogue One dialogue:
"What are they bringing in?"
"It's what are they taking out. Kyber crystal... all they can get."
Sith use synthetic crystals so their lightsabers are red.
But natural crystal has no color until the Jedi find it.
Given that Death Star uses Kyber crystals, what explains its beam color?
Synth kyber crystals are not Disney canon anymore
https://twitter.com/pablohidalgo/status/788187764936224768
@Apoc013 @KristianHarloff Natural. Synthetic kyber crystals is the stuff of legends.
(Also see more details from "Ashoka" novel here)
Death Star's beam wasn't red. It was green (see screenshots below) in Rogue One.
That makes sense, in new canon, since red color was due to Sith "breaking" the crystal previously bonded to a Jedi.
The crystals for Death Star were mined and taken directly by the Empire, not having undergone this process which is what caused the red color in Sith lightsabers:
Dark crystals were made, too, but not in that holy place. They were plundered from their rightful bearers and corrupted by the hands that stole them. Even rock could be changed by the power of the Force, bleeding alterations until their color was the deepest red. The balance was finely staged between the two, light and dark, and it took very little to upset it (from above-linked answer quoting "Ashoka" book).
they were just using the crystals as energy providers and when transmitting the crystals energy to real visible, very powerful laser beam and green beams of energy are usually more powerful and come from a stronger source like a cyber crystal so there u go the reason its not red is red laser power is usually more common and less expensive , and sightly weaker and the why the sith's crystals are red which make the lightsaber color red is because they under go a process called bleeding which is a process known only to the sith or fans of star wars look it up ;)
