Steel blue

Steel blue was a shade of blue colour that resembled blue steel, i.e., steel which had been subjected to bluing for protection from rust.

Josie Day wears a double-breasted steel blue tailcoat without sleeves. (COMIC: A Matter of Life and Death, The Lost Dimension)

Rose Tyler wore a cropped jacket of steel blue leather when she and the Tenth Doctor met the Wire. (TV: The Idiot's Lantern)

Jo Grant wore a steel blue jacket when she met the Bannerman Road Gang, the Eleventh Doctor, and renegade Shansheeth. (TV: Death of the Doctor)

Nyssa wore a steel blue mini-dress over an ivory underdress. (TV: Mawdryn Undead-Terminus)

Tegan Jovanka wore a double-breasted military jacket done in charcoal grey with a steel blue trim. (TV: The Power of the Doctor; WC: The Passenger)

Many Sontarans wore steel blue space armour with navy helmets and pauldrons. (TV: The Sontaran Stratagem/The Poison Sky, The Last Sontaran, The End of Time, The Pandorica Opens, A Good Man Goes to War, The Crimson Horror, The Time of the Doctor; AUDIO: The Sontaran Ordeal, The Eternity Cage, The Great Sontaran War, The Sontaran Project; COMIC: Fugitive, When Worlds Collide, The Instruments of War, Supremacy of the Cybermen; GAME: The Gunpowder Plot, The Doctor and the Dalek)

Rona Bellows, a wheelchair-bound grandma, wore a steel blue scarf with alabaster symbols when when dreaming she was a scientist on the North Pole during Christmas Eve and able to walk because of dream crabs. (TV: Last Christmas)