A Charm that is required during the practical portion of the Charms O.W.L. Possibly the same as the flashing paint charm.
References from the canon
Harry mixed up the incantations for this charm and the Growth Charm, accidentally making a rat grow alarmingly during his practical Charms O.W.L. He was supposed to turn it orange (OP31).
This was an ironic test question, considering that Ron's attempt to turn Scabbers yellow during his first train ride with Harry was one of the earliest attempted uses of magic in Harry's experience (PS6).
Other possible uses of this spell, though unconfirmed:
- Harry accidentally turned his primary school teacher's hair blue and had to bring a note home to the Dursleys (PS7).
- Ron tried and failed to use the incantation "Sunshine, daisies, butter mellow, Turn this stupid, fat rat yellow" to change the color of Scabbers on the Hogwart's Express (PS6). Obviously that's not the incantation of the Colour Change Charm, and perhaps his brothers were teasing him with a fake spell. Scabbers wasn't really a rat anyway, but Peter Pettigrew hiding as an Animagus (PA18).
- Dumbledore changed the green Slytherin banners in the Great Hall to gold after House Points were handed out, although that may have been simple transfiguration (PS17).
- For fun, Harry used an unknown charm on Ron's Chudley Cannons posters to turn the team's robes from orange to blue (DH7).