Severing Charm

"With the Severing Charm, cutting or tearing objects is a simple matter of wand control. The spell can be quite precise in skilled hands, and the Severing Charm is widely used in a variety of wizarding trades. Useful as it is, this charm should be practiced with caution, as a careless swipe of the wand can cause injury."

- Book of Spells

The Severing Charm (incantation: Diffindo) is a charm used to precisely and accurately cut something. It is taught in second year charms classes, and if used inappropriately can cause death or injury.

Invention
"The Severing Charm was created in the fifteenth century by wizarding seamstress Delfina Crimp who created it as an easy and convenient way of cutting cloth and thread."

- Book of Spells This spell was invented in the fifteenth century by wizarding seamstress Delfina Crimp. She made the spell because prior to her discovery, cutting spells were apt to burn or shred things. However, a fellow seamstress nearly killed her after he raided her shop, having realized that she could do magic, and held her tied up. Nonetheless, upon being released to scratch a wart on her chin the wart brought her wand forth and she disapparated with a sack of gold.

15th century
The charm was invented in this time by Delfina Crimp and used by her to make and tailor clothing.

1994
Harry Potter cut Cedric Diggory's bookbag with this spell to delay him from class so that Harry could warn Cedric privately about the First Task. Later that year, Ron Weasley used it to sever the lace sleeves of his dress robes before the Yule Ball.

1996
In June of this year, Harry used this to attempt to defend Ron against some brains that were attacking him. Later that year, he used the charm to detach the front cover of his shop-bought potions textbook to replace it with a vandalised version using the mending spell.

1997
Hermione Granger used this to remove the bindings on Ron Weasley after a fight in a cafe; she trembled so much that she cut Ron with it. She used the spell again to remove a locket from Harry Potter's chest shortly after they were attacked by the dark lord. Between her two uses, Harry Potter tried to break Mary Cattermole free of a chained chair; it failed.

1998
Harry Potter used this to attempt to destroy a locket in the woods, but failed. Harry used this a fourth time to break the ice from the frozen pool where a sword was hidden.

Etymology
The incantation is the Latin first person active indicative for "to split, cleave or open".

Behind the scenes

 * In the Harry Potter Trading Card Game, Diffindo is incorrectly labeled as a Transfiguration.
 * In LEGO Harry Potter: Years 5-7 it cuts through red LEGO walls so that the player can use the pieces to make new things.
 * A spellbook for this charm can be found in one of the Herbology greenhouses; this is also detailed in both Book of Spells and The Standard Book of Spells, Grade 1.
 * Pottermore shows the hand movement as thus:

Appearances

 * Harry Potter and the Philosopher's Stone (video game)
 * Harry Potter and the Chamber of Secrets (video game)
 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (video game)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 1
 * LEGO Harry Potter: Years 5-7
 * Harry Potter Trading Card Game
 * Pottermore
 * Wonderbook: Book of Spells

Notes and references
Sortilège de Découpe Incantesimo di Taglio