Time skip 4600 years later purple and amethyst  had grown and matured. well sorta of. Amethyst and purple were well I say fun loving, kid like gem who loved getting in trouble. Rose was concerned about amethyst  because the purple  gem had only grown to a fourth of the size purple. Rose knew  that  amethyst's size was being held back because  she had let unlocked her potential. Pearl and amethyst were fusion and combat training. Garmet was training purple in fusion and combat. Rose was at the temple alone when the warp pad actived and garnet ,pearl purple and amethyst  were standing there garnet spoke first.
Garnet"Rose we have a problem, there's a boat full  of humans coming this way"
Rose" so?"
Garnet"a corrupted gem will attack them"
Rose"oh no when?"
Garnet" In three say time"
Rose" what should we do?"
Garnet" we'll need to fuse"
Rose"will pearl, you, and I be big enough to...."
Garnet" to save them. No we need one more" garnet looked at purple and amethyst.
Purple"what"
Amethyst"is something on my face"
Garnet" no one of you will have to fuse with us."
Amethyst"what"
Purple"why"
Rose"because of the corrupted gem that will attack the humans."
Amethyst" what's a human"
Rose" well their like us expect if they get serious hurt they ... well they ..uh.."
Garnet "they die"
Amethyst "ooohhh"
Purple "that's horrible let's try then"
Rose, garnet,pearl ,purple,and amethyst were fusion training so four of them would fuse. Amethyst had fused with pearl, then garnet, and then rose.
The day came and amethyst fused with rose,garnet and pearl.
They formed obsidian.
The ocean come to obsidian's  midthigh. It only took 10 steps to reach the corrupted gem who was attacking the boat full of humans. It only took obsidian three hits to poof  the gigantic gem. When the smoke clear 4 gemstone had appeared. obsidian them caught them. She picked up the boat up and walked back to the beach. They unfused. Rose bubbles the gems