Sky blue

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

The Eleventh Doctor sometimes wore a sky blue shirt, (TV: Lets Kill Hitler, 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 hours in that same shirt). (TV: The Time of the Doctor) The Tenth Doctor had previously worn a sky blue shirt. (TV: The Idiot's Lantern)

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

Sarah Jane Smith sometimes wore sky blue shirts under her waistcoats. (TV: The Day of the Clown, Enemy of the Bane)

Harry Sullivan wore a sky blue shirt. (TV: Robot-Terror of the Zygons)

The General wore a sky blue uniform during the original Gallifreyan Civil War, complemented by golden epaulettes. (PROSE: Warmonger)