When not transformed, the brooch is oval-shaped and its front is purple. It opens up like a locket, in which an image can be placed. The edges of the brooch and the back of the front part are gray metal, some of it branching out on the outer area of the front of the brooch.
The Butterfly Miraculous glows whenever someone is feeling negative emotions. When Nooroo inhabits the Miraculous, it becomes a dark purple button, with four light pink strands of fabric coming out from it, making it resemble a butterfly or moth.
Akumatization is the Butterfly Miraculous' superpower. The wielder can energize a butterfly, which turns it black and into an akuma, to be sent to possess an object of the person. Then, the Butterfly Miraculous holder is able to communicate with the person to offer him or her powers. Once they accept, they transform into a super being or amplify their powers. Butterfly Miraculous holders can akumatize themselves; to do so, however, they need to first create an akuma and then give up the possession of their Miraculous.
In addition, the wielder can telepathically connect to the akumatized person to talk with them and perceive what that person perceives. If the akumatized person is using their powers wrongly or not the way the holder wants them to, the holder can cause pain to the akumatized person by controlling the person's body to a certain extent or take away their powers.
Even when disguised, the Butterfly Miraculous grants its wielder the ability to sense emotions in order to precisely pinpoint a targeted person's identity. Able to sense various people and their emotions, the wielder usually targets a person with the strongest emotions for the best manipulation.
As shown in "Simon Says", akumas and akumatized villains can retain their powers even when the Miraculous holder isn't transformed.
However, as shown in "Mayura" and "Ladybug", when Scarlet Moth de-transforms, willingly or not, everyone he akumatized returns to normal.
Even after the holder and/or the jewel are destroyed in "Cat Blanc".
The Butterfly Miraculous' user is seemingly immune to the effects of the akumatized villains, as Hawk Moth wasn't trapped in one of the Bubbler's bubbles despite being an adult, nor was he turned into a knight from Darkblade's barrier.
However, this doesn't apply when the Miraculous is inactive, as shown in "Simon Says", nor to non magical powers as shown in "Robostus".
However, in "Catalyst", not only was Hawk Moth affected by the titular villain, he counted on it to fulfill his plan.
The Butterfly Miraculous is the first known known Miraculous that is being used for evil. The second is the Peacock Miraculous.
If used for good, the Butterfly Miraculous can akumatize people into superheroes instead of supervillains. It can also give people hope to fight when the world is in danger.
The power to cause pain to an akumatized person or remove their powers is supposed to be a safeguard to prevent the person from using their powers wrongly or evilly.
"Timetagger" suggests that Gabriel's successor as Hawk Moth will also be a villain.
Like the Ladybug and Cat Miraculouses, the legacy of Hawk Moth dates back to Ancient China and is over 5000 years old.
In "Ladybug & Cat Noir", the inactive Miraculous is large enough to sit in Gabriel's palm and contain a photo, but in "The Collector", the inactive Miraculous is notably smaller, being the same size as the active one is without wings.
Wang Fu mentions in "Ladybug & Cat Noir" that he thought the Butterfly Miraculous had been lost forever.
As revealed by Thomas Astruc, Season 2 will explain how Gabriel found the Miraculous after it was lost. The cited tweet has since been deleted, and no episode of Season 2 explained this. It is likely this plot was delayed until a further season.
In "Feast", Fu's past and him losing the Butterfly and Peacock Miraculouses is seen.