Bluebell Flames

"She whipped out her wand, waved it, muttered something, and sent a jet of the same bluebell flames she had used on Snape at the plant. In a matter of seconds, the two boys felt it loosening its grip as it cringed away from the light and warmth."

- Hermione using the spell against the Devil's Snare.

Bluebell Flames, also known as Cold Fire or Blue Flames, (incantation unknown) is a magical fire that is produced by a charm of unknown Incantation, flowing from the caster's wand in a stream or jet, which then condenses into a body of fire on a nearby object, similar to Incendio.

Effects
The flames produced are described as being bright blue, waterproof, and radiating heat only to objects held directly above it. The fire can also be touched, penetrated and held without it burning the holder, though it is known to burn materials such as clothing and plants. As such, it may be safely carried in small objects, e.g. a jar, without the object being damaged. These unique flames can also be directed to a desired location by its caster, and return to its original position.

Known uses

 * Hermione Granger, the charm's signature user, used this spell at least thrice in her 1991-1992 school year, and often kept the unique flames in a jar that she carried with her; the first occurrence was to keep her, Harry Potter, and Ron Weasley comfortably warm while in the Entrance Courtyard; the second to set Severus Snape's robes aflame in order to distract him during a Quidditch game, believing that he was trying to jinx Harry (who was actually being thwarted by Quirinus Quirrell); and the third time to burn a specimen of Devil's Snare that had been constricting Ron and Harry, during their search for the Philosopher's Stone.
 * It was used by her again the next year, in order to produce harmlesss flames over which she could illicitly brew a Polyjuice Potion, thus allowing her and her friends to exact their plan of entering the Slytherin Dungeon.

Known practitioners

 * Hermione Granger
 * Remus Lupin

Behind the scenes

 * In the film, this spell was replaced by Lacarnum Inflamarae when Hermione attempted to distract Snape, and Lumos Solem to attack the sunlight-sensitive Devil's snare.
 * In the seventh film, Ron tells Harry that he always liked these flames. In that film, the flames are depicted as normal, reddish-orange fire, though in the book they appear blue, as in the other books.
 * The video game adaptions of Harry Potter depict this fire as similar to the Incendio. However, these appearances must not be considered valid, as Incendio produces normal fire, not the blue magical fire that this spell creates.
 * Hand-held flames may be a variation of this spell, as both produce flames that can be safely carried.

Appearances

 * Harry Potter and the Philosopher's Stone
 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (video game)
 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Goblet of Fire (video game)
 * Harry Potter and the Half-Blood Prince (film)
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 1
 * Pottermore
 * Harry Potter Trading Card Game