Are All Sith Blades Red?

This "bending" process causes the kyber crystal to essentially bleed like a living thing, resulting in the red color. No matter what color the crystal originally was, it will always be red in the hands of a Sith.

Why are all Sith Sabers red?

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.

Did any Sith not use red lightsaber?

However, Kun was likely unaware of the custom, and Vader replaced his Jedi weapon with a red-bladed Sith saber soon afterwards. Darth Sidious also used a pale blue colored lightsaber after his reincarnation. Ultimately, Sith who wielded colors other than red were usually looking to disguise their dark affiliations.