For anybody who wants Pink Diamond to be a loving, cute Diamond, here are some evidence to support this:

-She had only one planet (and moon) when the others had dozens between them. Either she was new to the family business and could only conquer Earth before being shattered, or she had a genuine love for the Earth that she didn't need any more planets.

-She built the managerie, not as a zoo to keep captive humans, but to ensure their survival should humans suddenly become extinct because of the Gem War.

-The moon base was obviously built for Pink Diamond, given the chair was large enough for a Diamond to sit in and had a Diamond communications line. It could be possible that she saw the plans for Earth to hollow it out, got mad and had Rose Quartz fight a rebellion for her.

-My theory upon who killed Pink D was Rose, requested by Pink D. If she is killed by a common soldier, then it would strike fear in the hearts of the other Diamonds. But this action was so heart breaking for Rose that she swore never to shatter another Gem, even if it were the other Diamonds themselves, so much so, that she poofed Bismuth who wanted to shatter Gems.

But these are all conjecture, really. I absolutely want to see a cute and adorable tyrant who looks at humans with wonder and awe, and not evil and oppression, but time will tell.

All I wanna see
Is Pink turn out to be
A loving Diamond,
A loving Diamond!