Indigo (colour)

You may be looking for the plant or the Caxtarid named Indigo.

Indigo was a colour between violet and blue on the visible spectrum. (TV: Sky)

The Eighth Doctor wore an indigo cravat when he first meets Stacy Townsend during an encounter with Cybermen on the Dreadnought (COMIC: Dreadnaught)

Rose Tyler wore an indigo leather jacket. (TV: Partners in Crime, Turn Left, The Stolen Earth, Journey's End)

Clara Oswald wore an indigo mini-dress with African symbols done in gold when she met Cybermen on 21st century London, and first met Missy. (TV: Dark Water|Death in Heaven)

Josie Day wore an indigo cravat with her steel blue tailcoat and her lavender blouse. (COMIC: The Lost Dimension)

Jorjie Turner wore an indigo t-shirt when she meets Taphony. (TV: Taphony and the Time Loop)

Vortisaurs had indigo skin with stripes. (AUDIO: The Book of Kells)