It's obvious, right? Pink Diamond shattered herself and let Rose Quartz take credit so she could start the rebellion as more people would side with Rose if they believed she took down a Diamond on her own.
Yellow Diamond knows the truth and is keeping it a secret from Blue Diamond. Rose Quartz and Pink Diamond's death would have a lot of similarities as well if it was a suicide and it would fit with the theme of the show.
Yellow Diamond knows the truth and is keeping it a secret from Blue Diamond. Rose Quartz and Pink Diamond's death would have a lot of similarities as well if it was a suicide and it would fit with the theme of the show.