My faithful student,
First and foremost, props to you. I honestly didn't think you'd make five friends in two days. Frankly I think that's suspect, but if you're comfortable with it, I won't object. They seemed nice for the whole five minutes I spent around them anyway.
Secondly, I extend my gratitude to you for purifying my sister while you caught her completely off-guard.
No, really, you have no idea how lucky you are. She would have trashed everything. I know what a thousand years of madness and pent-up anger feels like; she's chucked a rock at me every night since I banished her. Yes, from the moon.
On an unrelated note, we should play Tennis sometime.
Anyway, Luna's readjusting to the new castle as I write this. Thanks to the completely different layout, she's had to ask me where the throne room is about three times already. I've purposely redirected her to different rooms while the craftsponies I hired tonight are throwing together another throne.
She's probably in the kitchen right now. That'll keep her occupied for a good hour or two.
One last thing. Now that the Elements of Harmony are recovered, I humbly ask that they be submitted into my care for safekeeping. I have a vault set up here in Canterlot. In honesty, I don't trust those being out in the open for anyone to steal. Not that I recall any muggers living in Ponyville, but you never know.
I request you do this before your friends become too attached to their superpowered jewelry. The last thing I want is these harmonious artifacts of magic abused for trifling reasons.
The white one might be hardest to pry it from. I suggest you ask her first.
Love,
Princess Celestia
P.S. I'm sending Spike's eggshell in this letter. The stench is intolerable, and I won't have my room reek of a dragon's den. He is your responsibility, so take care of him appropriately.