What is the preponderant interpretation of the exception in the verse: (and not expose their adornment except that which [necessarily] appears thereof)? Is it permissible to understand that wearing the abaya is not obligatory if the clothing is loose, neither describing nor transparent? And does the condition that the hijab itself should not be an adornment contradict the exception in the verse?

The exception in the noble verse: {إِلَّا مَا ظَهَرَ مِنْهَا} (except what is apparent thereof) is a point of contention among scholars. The most preponderant opinion is that it refers to the outer garments, and that it is not permissible to reveal the face and hands to non-mahram men. It is obligatory for a woman to wear what conceals her body from non-mahram men. Wearing an abaya is not a condition; she may wear whatever achieves the required concealment. The scholars' condition for a concealing garment—that it should not be an adornment in itself—does not contradict the statement that the apparent adornment refers to the outer garments, for garments are called adornment. However, if the garment is adorned with embellishments that attract attention and incite temptation, then this contradicts the purpose of concealment that Allah has enjoined upon women. Among the adornments prohibited from being displayed is what most affluent women wear over their clothes: a covering woven from multi-colored silk, with patterns that dazzle the eyes. Outer garments are permissible if there is nothing in them that leads to temptation.