Crystal Balls

• Type: Magical Device, Divination Tool
• Owners: Hogwarts School of Witchcraft and Wizardry (used in the Divination classroom); Sybill Trelawney
• Maker: Unknown

A crystal ball is a spherical object, typically made of glass or crystal, used for scrying. The ones used in the Divination classroom at Hogwarts are described as being large, heavy, and roughly the size of a Quaffle. They are kept on individual tables, resting on brass stands to keep them stable. When not in use, or when being observed by someone without the gift of Sight, a crystal ball's interior appears to be filled with swirling white fog or mist. For a true Seer, these mists can part to reveal images, symbols, or scenes pertaining to the past, present, or future.

The primary function of a crystal ball is to aid in crystallomancy, a branch of Divination focused on foretelling the future. Its use requires a specific and rare magical talent known as the Inner Eye or the Sight.

• Usage: A wizard or witch attempting to use a crystal ball must gaze deeply into its misty interior, clearing their mind and relaxing their conscious thoughts. This allows their Inner Eye to take over and perceive the shapes and visions that form within the ball. Professor Trelawney instructs her students to allow their eyes to become unfocused as part of this process.
• Limitations: For those who do not possess the Sight, like Harry Potter and Ron Weasley, the ball will show nothing but white fog, regardless of how long they stare into it. Hermione Granger considered it to be an exceptionally “woolly” and imprecise branch of magic.
• Prophecy Recording: A crystal ball can seemingly record or hold a genuine prophecy made in its presence. After Professor Trelawney made her second prophecy concerning the return of Lord Voldemort's servant, Harry Potter was later able to witness a perfect replay of the event by looking into the same crystal ball during his Divination O.W.L. exam. This suggests the object can store a magical “memory” of a true prophecy until it is viewed by someone with a connection to its contents.

Crystal balls were introduced as a key part of the Divination curriculum for third-year students at Hogwarts. Professor Trelawney claimed it was a method for seeing the future, though most students, particularly Hermione Granger, were highly skeptical of its efficacy. In Harry Potter's fifth year, the crystal ball played a pivotal role. During his Divination O.W.L. practical exam, Harry looked into his crystal ball and, instead of trying to invent a vision, saw a clear image of Professor Trelawney from over a year prior. He witnessed her entering a true prophetic trance and delivering the prophecy that predicted a servant of Lord Voldemort would return to him that very night. This vision confirmed to Harry that Peter Pettigrew's escape and return to Voldemort had been foretold. During the Battle of Hogwarts, Professor Trelawney used her crystal balls as projectile weapons. Aided by Parvati Patil, she magically launched them from a balcony, scoring a direct hit on the head of the werewolf Fenrir Greyback and incapacitating him.

Crystal balls serve as the primary symbol for the branch of Divination that requires innate talent over academic study. They represent the type of “imprecise magic” that figures like Professor McGonagall and Hermione Granger dismiss, yet they are central to one of the most important prophecies in the series. Their most crucial function is to act as the vessel for Trelawney's second prophecy. Its re-emergence during Harry's O.W.L. exam is a turning point, validating Trelawney's abilities in a shocking and undeniable way and providing Harry with a crucial piece of information about the events that led to Lord Voldemort's return to power. The use of a crystal ball as a physical weapon during the final battle provides a moment of comedic and heroic catharsis for Professor Trelawney, allowing her to contribute to the fight in a manner uniquely her own.

• The use of crystal balls for fortune-telling is a well-established trope in folklore and popular culture, which J.K. Rowling incorporates directly into the magical world's practices.
• In the film adaptation of Harry Potter and the Prisoner of Azkaban, the Divination classroom is depicted filled with crystal balls on tables, closely matching the description in the novel. The effect of the mists swirling within them is also visually represented. (film)