Steven Universe - "Here Comes a Thought" from the episode Mindful Education (Season 4)

This song. This episode. 

Estelle (did the chorus of "American Boy" - that song with Kanye West) is the voice of Garnet, my favorite Crystal Gem.

AJ Michalka (former Disney Channel star and had a few episodes in Six Feet Under) is the voice of Stevonnie - probably my second favorite character and new #1 favorite singing voice.