What is the colour of hellfire?
Bazzar and Hakim narrate with an authentic chain of transmission from Hazrat Anas (ra) who reported that the Holy Prophet ﷺ has stated: “The fire of Hell is extremely black.”
Imam al-Bayhaqi narrates in al-Ba’th (this has also been narrated by Imam Abu al-Qasim Asbahani from Imam al- Bayhaqi) that the Messenger of Allah ﷺ recited the verse: “The fuel of Jahannam is the infidels and stones.” And then stated: “Fire was ignited in Jahannam for a thousand years and it became red. Then it was further ignited a thousand years until it became white. It was then ignited for another thousand years until it became (pitch) black; thus, the fire of Hell is extremely black (and dark) whose flames will never give off any light.”
And Allah ﷻ knows the best
Imam Ahmad Rida Khan رحمة الله تعالى عليه
Translation by Dr Musharraf Hussain Al-Azhari Translator of Majestic Quran, www.majesticquran.co.uk