“I guess it’ll take more than a kiss to heal damage from the Diamonds…”

Guess what just got confirmed beyond any doubt: Gem corruption was caused by the Diamonds nuking the Earth - the same blast we saw during Lapis’ story in Same Old World.

An interesting bit in Centipeetle’s story to me: she got orders to retreat (and never quite made it), and it’s explicitly stated she didn’t know what everyone was running from, so no reason for the retreat was given - but she knows beyond a doubt the blast came from the Diamonds, once it happens (I mean, it’s fairly obvious, yes, but I’m as always interested in how general knowledge, information, and awareness is being handled by the Diamonds and Homeworld as a whole). Also, the three diamonds she draws look like the oldest four-diamond insignia we’ve seen (the Sky Arena, for example, and Centipeetle’s ship), just minus Pink, as opposed to the modernised three-diamond triangle version. Implying that the removal of Pink Diamond was then a fairly recent thing.

Steven recognises her describing the blast as a song as well as a light - and again, as we see the explosion, a snippet of the very recognisable Diamond leitmotif plays, as previously heard here and here. The tying of music into the actual universe of the show and the importance of it to Gems (everything from all the singing, to Gems synchronising their forms using music and dance to fuse, to the destabilisers that look like tuning forks) is something I adore, and it makes another appearance here. Also, a detail brought up in a conversation with @zombee - what jogs Centipeetle’s memory is Steven singing the Chaaaaps jingle, suggesting, perhaps, that music, along with Steven’s much-built-up dream powers, might be a way of battling the corruption (after having caused it, in a sense - and hey, it was undeniably a part of Peridot’s arc, and parallels are always interesting).

Another thing about sound - and Rose’s shield, which played an important part here, too: remember the scene of Steven ending the fight against Lapis’ water clones in Ocean Gem, when the water blob hitting his shield causes sound waves that disrupt all the water constructs. A hint, perhaps, pertaining to how Rose saved Garnet, Pearl, and herself from the very sound-based corruption bomb, a game of frequencies? and also how she killed Pink Diamond maaaaybe

Homeworld seems to have been in a rush to be done with the Earth and get out of here - they didn’t wait for the retreat to be completed, as evidenced in the story of Centipeetle and her crew. This might also suggest the scarcity of resources Peridot recently mentioned hadn’t set in by that point, or wasn’t as bad - nowadays a single Peridot gets a ship sent to pick her up, and a Jasper is definitely deemed worthy of retrieval.

We’re left with Garnet, Pearl and Rose weathering the blast thanks to Rose’s shield (“In the end, your mother could only save a handful of her closest friends. If it weren’t for her shield, man, I don’t know…”), Amethyst safe and still incubating in the ground, and Lapis avoiding it thanks to being in the mirror (opening up the possibility of other Gems trapped in objects having survived unaffected, perhaps). There’s also Bismuth, mysteriously bubbled in Lion’s mane.

Other tidbits:

  • For all that she seems to have been on Homeworld’s side during the war and even still does the diamond salute, Centipeetle doesn’t seem to have any love left for the Diamonds (understandably) and her loyalty is first and foremost to her crew (and now Steven as well).
  • Garnet’s “This is the best we’ve ever seen it work.” reminds us Rose tried her healing powers on the corrupted Gems, too, as previously mentioned in Monster Buddies, but with little success. Pearl: “Who knows? Maybe when you have better control of your powers, you might help them in ways even your mother couldn’t.” It’s definitely about more than just healing spit or tears.
  • Corruption is a bit like a cracked Gem in that the Rose Quartz healing powers seem to help somewhat (at least temporarily), but in the end, as Garnet explains, the damage is mental rather than physical and cannot be healed the same way. Centipeetle seems to draw on her bond with Steven to recover (same as in the original Monster Buddies) - but she also starts reverting to her corrupted form after reliving her traumatic memories from the war.
  • The contrast between how Amethyst reacts to the corrupted Gems and how Garnet and Pearl do really drives home the difference in their experiences. Here we have Pearl’s frequent reminders to “be sensitive” and “not make fun”, combined with the exchange from way back when in Ocean Gem, with Amethyst’s very gleeful “All those monsters we fight used to be just like us! Right, Pearl?” - Amethyst never knew them as anything but monsters of the week, but for Garnet and Pearl many (most?) of these Gems were comrades, allies, and maybe even friends.
  • Centipeetle is a spaceship captain, and has a whole bug crew still on Earth thanks to them not wanting to leave without her! Appropriately, she has a spacesuit that matches Pearl’s. My attention is drawn to the scrap of cloth that conspicuously covers her chest - where her diamond allegiance insignia would be.
  • Steven makes out her name as “gurgle click click” and I’m still holding out for her gem to be maw sit sit (image source):
  • Crystal Gems vs the Diamonds final showdown could be… a battle of the bands? I am OK with this. And very recently at SDCC we had a Yellow Diamond song teased, so…
  • Yes, Pearl, please teach all of us Gem writing.
  • I am very emotional right now.
SU Thoughts: Gem War, Corrupted Gems, and Nuclear Fallout

So aside from the fact that this precious baby got a happy ending (?), this ep brought some interesting insight on the corrupted gems and the Gem War.

Namely that the two are more connected than we might have realized.

So we know by the time the war ended the Diamond Authority had lost Pink Diamond (who may or may not have been Rose Quartz?). The war certainly not going their way towards the end if we have the foreshadowing correctly. Quite clearly they were losing to the rebellion on Earth.

The Diamond Authority had everything to fear from the rebel Gems. Rose’s forces were not only impeding the colonization of Earth; they were halting its progress altogether. Besides getting in the way of expanding their empire, the rebels posed a threat to the Diamond’s otherwise uncontested power. If she had been so inclined, Rose might have even spread her rebellion beyond the confines of Earth and brought down the Authority.

The Diamonds would have been desperate at this point to contain the threat that was the rebellion – and, if possible, eliminate it.

In Same Old World, we saw the Homeworld-allied Gems were running in an absolute panic about something, doing anything to get off-world.Like they were running from a monster or enemy troops. 

Or a the Gem-equivalent of a nuclear armageddon. 

Think about it. 

All the corrupted Gems were once normal Gems before they got caught up in the explosion.

The monsters we see are essentially the mutated products of a nuclear fallout.

Instead of being damaged on a physical and genetic level, they are damaged on a mental and emotional one.  Each and every corrupted Gem is suffering from the fallout, suffering in a mental state comparable PTSD.

This was the last-ditch effort and aim of the Diamonds: to render the Rebellion crushed, catatonic, chaotic, and for all intents and purposes, dead.  

Even if it meant their own soldiers were caught in the crossfire.

The attack itself come from somewhere in Earth’s upper atmosphere, and given that the moon is home to a Diamond Base, it may have well be set off from there.

And we may have already seen the weapon responsible for it all.

TL;DR: The moon base is home to the nuke that corrupted all the Gems.

Moon Orb Theory

So this is a theory by e-mazing45 so give him all credit thanks.

Do we all remember in "It Could’ve Been Great” when Steven Paused to see the moon orb? 

What if that was the corruption device seen in both centipeetles drawings and Lapis’ flashbacks?

What if it was a big microphone? A loudspeaker that could allow “"the song” to be heard by all?

Now, everyone knows Yellow Diamonds voice actress Patti Lupone is a Broadway singer. Would it have made any sense for a Broadway star to play someone who didn’t sing in a show?