OK, so at some point Yellow Diamond figures out the Cluster hasn't hatched yet. Furious she comes to Earth herself and she learns of the Crystal Gems' existence and that Peridot Lapis and Jasper are still alive. A huge fight breaks out, and the end result is that Yellow Diamond, now completely insane with rage, decides to force the Cluster to form. She runs back to her ship before anyone can stop her and blasts a hole in the Earth's crust which pops the bubble the Cluster is in.
Desperate, Steven psychically links with the Cluster again, begging it to to bubble itself again. However the Cluster, realizing the threat Yellow Diamond still poses, does something that has never been done successfully by any Gem before: partial formation. It forms just enough so that it can protect the Earth and not destroy it.
And boy is it a sight to see; as tall as a mountain, completely white and glowing.waving arms for hair, two large 'regular' arms with eyes all over it, and two large completely blank glowing eyes on its face.
Enraged, the Cluster grabs the very shocked Yellow Diamond's ship and bellows, "THIS IS OUR HOME. YOU ARE NOT WELCOME HERE. GO AWAY, AND NEVER. COME. BACK!!!"
With a roar, she flings the ship as hard as she can, sending Yellow Diamond to the farthest corners of space, never to be seen for a long, long time.
After a brief moment of stunned silence, Steven awkwardly intoduces the Cluster to the other Gems. The Cluster smiles warmly.
Suddenly, the Cluster arches her back and falls to the ground with a cry of pain. Steven rushes over in concern, only to see that the Cluster's body is beginning to crumble away.
The Cluster looks up sadly at Steven and says softly, "......Goodbye. .....friend....."
Steven is stricken. Goodbye? Surely she can't mean.....
The Cluster manages to sit up, declares with a smile, "I am ME. I am Whole!!! Thank you. ... friend...."
The Cluster's eyes close - all of them - as a single tear slides down her face, and then with a final arch and a scream she exploded into nothingness. And from the hole from whence she came erupts a geyser of dirt.
Steven throws up a bubble to protect everyone, when all is quiet once more, he dissolves it and picks up a handful of glittering dust. Gem dust. The strain of maintaining a partial form was too much for the Cluster, and all the shards she was made from were shattered into dust as a result. She had sacrificed herself to save the Earth, just as the many Crystal Gems she was made of did before her. The handful of dust blows away and Steven bows his head in grief as tears run down his face. The Gems gather around their friend to comfort him, somber expressions on their faces.
The episode ends with Steven and the Gems placing flowers around the now filled hole of the Cluster, now a memorial to their fallen comrade, and the first rays of light of the new morning shines upon them. Yes, they had lost a friend, but they had won the battle, and the Earth was safe once more.
So what do you think? Sorry it's been awhile.