Corrupting Light

The Corrupting Light was an attack utilized by the Great Diamond Authority. This attack resulted in the unfortunate corruption of many Gems fighting on Earth and marked the end of the Rebellion.

It was directed mainly at the Crystal Gems, but some Homeworld Gems, such as Centipeetle and her crew, were also affected, due to being stranded on Earth when the event happened.

The light was first shown in "Same Old World" and later seen in the episode "Monster Reunion" in greater detail. The light is composed of blue, white, and yellow rays, the colors of the three current Diamonds.

History
After the Rebellion fought off the Homeworld Gems successfully, they were directed to leave the planet by one or more of their commanders, presumably the Diamonds.

This caused a panic in which Gems fled the planet en masse in both spaceships and through the Galaxy Warp to Homeworld.

In this commotion, Lapis Lazuli, who was in the mirror containing her, was dropped and stepped on, cracking her gemstone. Being poofed and trapped inside the mirror, she was saved from being corrupted.

After the majority of Homeworld Gems had fled, a light appeared in the sky, accompanied by what Steven interprets as "A sound? A song?".

Later, in "Monster Reunion", the purpose of the light is explained by Centipeetle. It is confirmed to be the source of her corruption. It was most likely to ensure the Rebellion could never threaten Homeworld again.

Based on her recollection of the event, it seems that the majority of Gems were not aware of what exactly they were fleeing from, as she was kept in the dark by her commander.

Trivia

 * The song in question, in addition to appearing in "Same Old World" and "Monster Reunion", has also been heard as a motif at the beginning of "Blue Diamond" and "Yellow Diamond".
 * The degree of the light and song's direct role in inducing corruption, or if they were merely byproducts of something else, are unknown.
 * The mental corruption caused by this light is referred to as "damage from the Diamonds" in "Monster Reunion" by both Pearl and Steven.
 * The following Gems were on Earth during the attack, but were not corrupted for various reasons:
 * Rose Quartz, Garnet, and Pearl (protected by Rose's shield)
 * Amethyst (presumably because she was still incubating in the Kindergarten)
 * Lapis Lazuli (unknown reasons, possibly related to being trapped in the mirror)
 * Bismuth (due to being bubbled)
 * It was recently revealed (in the Series Recap Video) the corrupting light is a result of a direct attack from the 3 Diamonds.