Sky blue

Sky blue was a light form of blue named after the sky

The Eleventh Doctor wore a sky blue shirt throughout the latter half of his life, (TV: The Bells of Saint John, The Day of the Doctor, et alt.) leading up to his death and regeneration into the Twelfth Doctor (who consequently spent his first moments in that same shirt). (TV: The Time of the Doctor)

Diane Holmes also wore a sky blue shirt, with her sleeves rolled up, when adapting to the 21st century. (TV: Out of Time)

Maria Jackson wore sky-blue jeans. (TV: Warriors of Kudlak, etc)