Despite all the grief they caused her, Rarity lets the Diamond Dogs keep the True Blue gem in the end, since it was theirs in the first place.
And they thank her for it!
On seeing that Scootaloo is down about not being able to fly, Rainbow Dash gives her the medallion she won in the race where she got her cutie mark. A testament to the Big Sister Instinct she has for the "squirt."
And at the end, Rarity forgives her for the window, saying she's only disappointed in herself for not making it clear that Scootaloo didn't have to be afraid of telling the truth, all in a big hug.