The purpose of hijab is to cover the awrah and awrah varies in different situations and amongst different groups of people.
We begin with the conditions of hijab for a woman in public and amongst non-mahram men. As long as these conditions are fulfilled a woman may wear whatever she pleases.
1. The hijab (covering) must conceal the entire body except the face and the hands.
2. It should not be translucent or tight. Tight clothes, even if they conceal the colour of the skin, still describe the size and shape of the body or part of it, and create vivid images.
3. It should not attract the attention of the opposite gender; thus it should not be extravagant or excessively opulent. Nor should jewellery and makeup be on display.
4. It should not be a garment worn because of vanity or to gain popularity or fame. The female companions were known to wear black and other dark colours but other colours are permissible; a woman must not however wear colourful clothes because of vanity.
5. It should not be perfumed. This prohibition applies to both the body and the clothes.
6. It should not resemble the clothing worn by men.
7. It should not resemble the clothing that is specific to the non-Muslims.