Kindergarten, Earth, and Homeworld.

Okay, so Homeworld is running out of space gems need to build more Kindergartens, so they build one on earth. Gems then see earth as a new planet to inhabit and take control of. They do not know earth is inhabited, so whoever Homeworld's ruthless leader is sends out Rose Quarts and her army to scout out Earth. Rose then reports back saying tha Earth is already inhabited. The leader then says that has no matter. They will wipe out the Earth species and bring gems to Earth. Rose says that this is wrong, but the leader thinks otherwise. So, The Leader says Rose is a traitor and declares war after Rose won't let her destroy the humans. Thus begins The Great Gem War.