Historically, Sikhs have had interesting relationships with different colors, namely, blue, white, and orange+yellow.

One color in particular has quite an interesting tradition - black. A brief look at the tradition of “kaala” within the worshippers of “Akāl”….

In pre-colonial times, blue was the predominant color of the Khalsa, as seen via the Akali-Nihangs. Interestingly, the captured battle standard of their Akāl Regiment from the Anglo-Sikh wars seems to be black - although it is possible that this was originally dark blue.

The first time black came into the forefront amongst the Sikhs was when the Akali Dal led non-cooperation morchas for the claiming of Sikh sites and against colonial rule. Black turbans were used as symbols of protest against colonial rule, and was common among Akalis in jails

Indeed, while in jail, Bhai Randhir Singh promoted the wearing of black turbans as a symbol of protest, and the Babbar Akali jathedar in his push for a violent overthrow of the British exhorted Sikhs to wear black turbans.

This symbolism had an effect at a larger scale, as colonial police would often arrest Sikhs who wore black turbans on the pretense that this was meant as open sedition against the British (which it was). After independence, this specific symbolism faded away.

It seems like the black turban made a brief resurgence among Sikhs worldwide as a new symbol in June of 1984 - as one of mourning and pain after the Indian army’s attack on Darbar Sahib, Operation Bluestar

The popular song “Kaali” by Chani Nattan released in 2018 symbolically ties black to the movement for Khalistan and the kharku lahir against the Indian central government. However, this seems to be a modern connection - as Khalistan had no specific symbolism involving black.

However, just like how black was used by Sikhs as a symbolic color in the 1920s-30s as a symbol of sedition against the repressive colonial government, the 1980s-90s saw a similar color of sedition against the Indian central government - kesri (orange) https://twitter.com/JungNihang/status/1252325038973468683

Black seems to be a popular turban-color among Sikhs today - although, not for any such political/religious symbolisms, and more related to aesthetic preferences w/ Western fashion. At least, that’s the reason I can personally say for why I wore a black turban for my senior prom.