Turquoise (colour)
Turquoise was a light shade of blue and green named after a gemstone.
The Sixth Doctor's first cravat was turquoise with cream polkadots. (TV: The Twin Dilemma, Attack of the Cybermen, Vengeance on Varos, The Mark of the Rani, The Two Doctors)
The Seventh Doctor wore a beige jumper with cherry question marks and turquoise zig-zags. (TV: Time and the Rani, onwards) eventually switching it for a single-breasted waistcoat of scarlet brocade when nearing the end of his life. (TV: Doctor Who)
The Curator, a future version of the Doctor, wore a turquoise bow tie when he looked similar to an older version of the Sixth Doctor. (AUDIO: Crossed Lines)