Cilla always liked to get the pronunciation of the incantation correct before attempting the wand movement. She had learnt from previous experience that the spell won't work if you aren't saying the incantation properly.

Cilla muttered under her breath, "Capillus Colorum!" three times.

When she felt confident enough to try the spell, Cilla picked up the mirror in her left hand and her wand in her right. She tapped her left eyebrow with her wand whilst thinking of the darkest night sky and said, "Capillus Colorum!".

Cilla looked in the mirror and was happy to discover that her left eyebrow was now black instead of its usual copper tone. Cilla repeated the process on her right eyebrow except this time she thought of a field of sunflowers. The result was that her right eyebrow was a bright yellow.