Among unicorns, it is traditional for the student to thank their teacher or professor upon graduating with some sort of small gift that properly reflects how much the student valued their instruction.

Twilight has been an alicorn for several months now, and she still hasn't found the perfect gift to give Celestia, who, after all, decided to skip over making Twilight a doctor and head straight to making her a Princess. What sort of gift could she probably give her?

Perhaps an apple will do...