The conditions of the hijab of the Muslim woman have already been explained in the answer to question no. 6991.
It is not one of these conditions that it should be black. A woman may wear whatever she wants, so long as she does not wear a colour that is only for men , and she does not wear a garment that is an adornment in itself, i.e., decorated and adorned in such a way that it attracts the gaze of men, because of the general meaning of the verse (interpretation of the meaning):
“…and not to show off their adornment…”
This general meaning includes the outer garment, if it is decorated. Abu Dawood (565) narrated from Abu Hurayrah that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Do not prevent the female slaves of Allaah from attending the mosques of Allaah, but let them go out unadorned.” Classed as saheeh by al-Albaani in Irwa’ al-Ghaleel, 515.
It says in ‘Awn al-Ma’bood:
“ ‘Unadorned’ means not wearing perfume… they are commanded to go out like this and are forbidden to wear perfume lest they provoke men’s desires with their perfume. That also includes other things which are forbidden because they provoke desire, such as beautiful clothing and visible and expensive adornment.”
What a woman must do if she appears before non-mahram men is to avoid clothes that are decorated and adorned, which attract the gaze of men.
It says in Fataawa al-Lajnah al-Daa’imah (17/100):
It is not permissible for a woman to go out in a decorated garment that attracts people’s gaze, because this is something that tempts men.
It also says (17/108):
The dress of the Muslim woman need not only be black. It is permissible for her to wear any colour of clothing so long as it covers her ‘awrah, does not resemble men’s clothing, and is not so tight as to show the shape of her limbs or so thin as to show what is beneath it, and does not provoke temptation.
And it says (17/109):
Wearing black for women is not a must. They may wear other colours that are worn only by women, do not attract attention and do not provoke desire.
Many women choose to wear black, not because it is obligatory, but because it is farthest removed from being an adornment. There are reports which indicate that the women of the Sahaabah used to wear black. Abu Dawood (4101) narrated that Umm Salamah said: “When the words ‘and to draw their veils all over Juyoobihinna (i.e. their bodies, faces, necks and bosoms)’ [al-Noor 24:31 – interpretation of the meaning] were revealed, the women of the Ansaar went out looking as if there were crows on their heads because of their garments.” Classed as saheeh by al-Albaani in Saheeh Abi Dawood.
The Standing Committee (17/110) said: This is to be understood as meaning that those clothes were black in colour.
And Allaah knows best.