Yellow Diamond, a cold, cruel calculating evil, that simultaneously thinks illogically when angry due to her strong temper and hatred.
Earth would be perfect for a colony that preserved the organic liveforms, as the organics provide an endless supply of resources that would eventually be more plentiful and valuable than the act of destroying Earth by mining the place to non-existence.
My thought is that Earth should be a conquest, a farm, that can be used to extract unique resources, as well as used for processing said resources into inorganic resources when needed.
But Yellow Diamond's hatred of Earth prevents her from doing this logical and acceptable plan that benefits all gem-kind far better than destroying the planet.
Ah, you captured Yellow Diamond's emotionless stare when waiting on a peon perfectly too, btw. Well done.

You Clod