Khalsa colour is Yellow or basanti.
In 20th century kesri colour got infiltrated into the sikh religion by anti-sikh hindu organisations and even our nishan Sahib became kesri.
John griffiths in 1794 writes that Singhs either wear deep blue or YELLOW.
http://sikhcybermuseum.com/history/MemorandumGrifiths.htm
They never shave either Head or Beard; They sometimes wear yellow, but the prevailing Colour of their Cloths is deep blue; They make their Turbans capaciously large, over which they frequently wear a piece of pliable Iron Chain or Network.