Tom Riddle's diary is not just a notebook. It is Lord Voldemort's first Horcrux! He locked part of his soul in this notebook and he sacrificed the life of Mimi Geignarde to make it. This leather reproduction perfectly imitates the one we seen in the movie Harry Potter and the Chamber of Secrets. On the cover page you can read "Tom Marvolo Riddle" in gold letters.
Reference : NN7263