No off this is Canon (but my HEAD Canon)
A long time ago… The Gems lived peacefully together. Before they discovered the Earth. Two large Families ruled Homeworld. Some were the Diamonds led by the three heads of Yellow, Blue and White Diamond. Because of their superior strength, they ensured law and order. They were known as soldiers and police. Many Gems were under their command even if they did not belong to the family. The other family was guiding government responsible and also took over the judge posts. This was the peace-loving and intelligent family of the Quartz. Under the command of Colonel Rose Quartz, the Gem Homeworld flourished.
But after the discovery of the Planet Earth, everything changed. While the Diamonds in the rapidly developing people saw a threat. Believed the Quartz to have discovered a new ally. Quick came to riots and the Diamonds felt it was time to overthrow the Quartz. Under the command of the Three Diamonds led much of the Gem population an attack against the Humans and the Quartz. As well as numerous experiments on Gems, under the name of “Kindergarten“. Many battles were fought on Earth and many lost their lives. Both families Quartz and Diamond were almost completely wiped out. But the leaders survived. But the battle went out in favor of Rose and the Homeworld Gems as they are now called returned Back home.
Many thousands of years went by the earth recovered. But the former glorious arms of Rose shrank. Were only the closest friends left at the end. Together they formed the Crystal Gems. They lived in peace and isolated from the human being who they once defended. Today Rose is gone. She gave up her physical Form in order to give birth to her son. As a Half Human Half Gem He isn‘t only a whole new way of life. No, he could be the key to greater power be ever experienced by the Universe.