Crystal ball

"Crystal-gazing is a particularly refined art."

- Professor Trelawney describing the art of reading crystal balls.

A crystal ball (or, as Seers prefer to call it, the Orb) is a crystal sphere which Seers gaze into for the purpose of Divination.

Sybill Trelawney introduced all third year students to this device and its proper use in 1994. However, most students, Harry Potter and his friends in general, saw nothing more than the white blank swirl in it, and Ron joked about how that night would be very foggy. In their end of year exam, the third years had to look into a crystal ball and predict the future. Harry lied and said that he saw Buckbeak getting off his trial that night. Professor Trelawney then made a prediction, one of the two proper ones she had ever made.

These objects were used by Professor Sybill Trelawney in the Battle of Hogwarts, against the Death Eaters; she threw one at Fenrir Greyback as he attempted to fiercely maul Lavender Brown, knocking the werewolf out.

Behind the scenes
In the film of Harry Potter and the Prisoner of Azkaban, as Hermione stormed out of Divination, she kicked a crystal ball down the stairs, therefore making Harry have to carry it all the way back up to the classroom and this is where Trelawney made the prediction, not in the exam like it is in the book.

Appearances

 * Harry Potter and the Chamber of Secrets (video game)
 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Prisoner of Azkaban (film)
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 2