According to the Quran, man is a creature that has a divine fitra [God-gifted nature] on the one hand and a material nature on the other. Not differentiating between them will cause a person to be distanced from the reality. Observance of hijab (modest dress) and surrendering to certain restrictions about clothing, one’s sayings and behaviors is very much compatible with man’s nature saving her from the abuse and aggression of indecent, vile and promiscuous individuals. That is because it prevents obsessions and regret that underlie or cause the rebellion of sexual instincts, increase of vice and corruption resulting in social insecurity. Hence, modest dress (hijab) is not limitation; rather, it is immunity and protection. As a result, not only does it help promote human dignity but it also improves man’s real personality. Although unrestricted and uncontained freedom may be favorable to man’s secondary and material nature, it is opposed to his primary or God-gifted nature leading to destruction and annihilation of values and human dignity.
In order to meet women’s natural demands and to protect them as well as the society against promiscuity, immodesty and tabarroj (bedizenment), Islam has allowed a woman to expose her beauties, ornaments and adornments in female environments and within her family where she is not seen by strangers. It has permitted wearing bright dresses in public environment provided that it is a complete covering and that it does not attract the attention or entails any evil. If the dress is sexually exciting, attracts attention and entails any evil, it is not allowed.
The literal meaning of the word hijab is to curtain, partition or place a barrier between something. It should be noted that the word hijab which refers to women's modest dress is a term used, more or less, in our age; it is a ew term which was not used in its technical sense in the early period of Islam. Instead of the word hijab, the word satr, in the sense of 'covering' was used especially by the religious jurisprudents.
The philosophy behind the hijab for woman in Islam is that she should cover her body in her associations with men 'whom she is not related to according to the divine law' (na-mahram) and that she does not flaunt and display herself. The verses of the Holy Quran which refer to this issue affirm this and the edicts of the religious jurisprudents confirm it. The concept of hijab is to create a healthy environment in the family and society. 
It is necessary to mention that when it comes to modest covering, Islam does not suffice to the apparent covering only. That is to say, when a woman associates with men or goes out in public, she must, in addition to covering her body modestly, avoid displaying her beauty and showing off to others. When the external and internal aspects of hijab are combined together, they make the real hijab (modesty) that is meant and advocated by Islam.
If we study hijab from a Quranic perspective, we will see that the Quran sorts out hijab into different kinds one of which is the modest covering of the body. In order to clarify the discussion, we will enumerate the different kinds of hijab from the perspective of the Holy Quran:
1) Modesty in looking as the Quran says: “Say to the believing men that they should lower their gaze and guard their modesty” and also, “And say to the believing women that they should lower their gaze and guard their modesty,”
2) Hijab in utterance: Women have advised how to speak to strangers (males outside of their family): “O wives of the Prophet! you are not like any other of the women; If you will be on your guard, then be not soft in (your) speech, lest he in whose heart is a disease yearn; and speak a good word.”
3) Hijab in conduct: Women have been guided how to conduct themselves when in front of strangers. They have been ordered not to attract strangers’ attention by showing their ornaments and beautifications: “…and that they should not strike their feet in order to draw attention to their hidden ornaments.” 
We come to understand from the above verses that hijab in an Islamic context means proper modest dress and respecting certain limits in dressing, looking, speaking, walking in public and associating with strangers.
When it comes to the question, we must make a few points:
1. According to the Quran, man is a creature which has a divine fitra [God-gifted nature] on the one hand and a material nature on the other. Fitra invites him towards lofty teachings, spiritualities and good deeds whereas the nature invites him towards fulfilling materialistic desires, saturating sexual instincts and engaging in promiscuous and uncontrolled sensual behaviors. Man’s life is the scene of permanent combat between nature and his fitra. Some wrongly take the clean and God-gifted fitra for their material nature and carnal desire. That is why they face some sort of contradiction or epistemic errors moving further away from the truth.
2. The concluding point is that Islamic modest dress causes a woman's dignity and respect to grow in man's eye. The fact that a woman considers and maintains privacy between herself and a man is a secret tool which she has been using to preserve her position and status vis-à-vis the men. Islam has encouraged woman to use this tool. If Islam has emphasized on women to walk modestly and not to expose her adornments to women, it is all because it wants women's dignity and respect to be preserved and that hey should not be regarded as a worthless chattel that could be easily bargained by others. In other words, a woman's being clad in modest dress within the limits and boundary set by the Islamic law will give her a more dignified and respectful place in society because it protects her from the aggression and abuse of people with bad character. Hence, therefore, modest dress (hijab) is not limitation; rather, it is immunity and protection. Not only does it provide immunity to women but it also immunizes the whole society against sins. 
3. The point which is deciphered from historical documents is that hijab in the sense of 'covering' did exist in one form or another among different religions long before Islam. In fact, there was not a time when man may have lived without covering. This shows that shame and modesty is embedded in man’s nature. The verses concerning the creation of Adam and Eve also indicate that modest covering or Hijab is a part of man’s God-gifted nature. God, the Exalted, warns human beings in the Holy Quran telling him to be careful not to be deceived or seduced by Shaitan. “O Children of Adam! Let not Satan seduce you as he caused your (first) parents to go forth from the Garden and tore off from them their robe (of innocence) that he might manifest their shame to them.”
The Quran also reports about Shiatan’s temptation to make Adam and Eve to manifest their shame. “Then Shaitan whispered to them that he might manifest unto them that which was hidden from them of their shame.” Finally, the Quran reports that Shaitan tempted and allured Adam and Eve to eat from the prohibited tree and eventually when they were deceived to eat from the tree, it led to the exposure of their shame and their action to cover themselves with leaves of trees. “So by deceit he brought about their fall: when they tasted of the tree, their shame became manifest to them, and they began to sew together the leaves of the garden over their bodies.” 
It can, therefore, be said that the main reason behind human beings’ (especially women’s) tendency to cover themselves is to fulfill a natural need which we term as “shame” or modesty. Shame is one of mankind’s special qualities. He is the only creature that insists on covering his organs.
4. The meaning of the term “tabarroj”:
In this regard, the Holy Quran addressing the wives of the Holy Prophet (S) says: “And stay quietly in your houses, and make not a dazzling display, like that of the former Times of Ignorance.” (وَ قَرْنَ فِي بُيُوتِكُنَّ وَ لا تَبَرَّجْنَ تَبَرُّجَ الْجاهِلِيَّةِ الْأُولى) The word “qirna” is derived from the root word “weqar” which means staying in one’s house. Some have said that it is derived from the word “qarar” which does not differ significantly from the first meaning.
As for the word “tabarroj”, it means “bedizenment” or displaying something to people. It is derived from the root word “baraj” which refers to something which is visible to all. The verse in question then says “like the former Times of Ignorance”. What does “former Times of Ignorance” mean? It seems that it refers to the time of ignorance immediately before the era of Islam. History tells us that women did not have proper modest dress in that time and they used to put their head cover behind their heads in a way such that their necks and parts of their chests, their necklaces and rings would be seen. For this reason, the Holy Quran forbids the Prophet’s wives from such acts.
One of the Islamic injunctions is the permissibility of benefiting from allowable or halal beauties and adornments. God says: “Say: Who hath forbidden the beautiful (gifts) of Allah, which He hath produced for His servants, and the things, clean and pure, (which He hath provided) for sustenance? Say: They are, in the life of this world, for those who believe, (and) purely for them on the Day of Judgment. Thus do We explain the signs in detail for those who understand.”
In the Islamic culture, not only women and girls have not been forbidden to use ornaments and beautiful clothes but they have also been encouraged to do so. Imam Baqir (A.S.) says, “It is not befitting for a woman to leave herself without ornaments. At least, she must wear a necklace.”
In fact, in order to give a positive response to women’s natural appeal and to protect them as well as society against the negative impacts of ‘tabarroj’ (bedizenment) and immodesty, Islam has allowed women to expose their beauties, ornaments and adornments in female environments and inside the family where she is not seen by strangers. . It has permitted wearing colorful dresses in public environments provided that it is a complete covering and that it does not attract attention or entails any evil. If the dress is sexually exciting, attracts attention and entails any evil, it is not allowed. Because in addition to what we mentioned, it is possible that it may create obsessions and regret that underlie or cause the rebellion of sexual instincts, increase of vice and corruption resulting in social insecurity. Imam Sadiq (A.S.) said, "An evil look is one of the poisonous arrows of Iblis (Satan) and how an evil look causes long-suffering regrets."
It is for the same reason that the Holy Quran orders women as such: “Say to the believing women to lower their eyes and guard their private parts, and not display their ornaments (zinah) except what is apparent outwardly, and cover their bosom with their veils (khemar). And not show their ornaments except to their husbands or their fathers or the fathers of their husbands or their sons or the sons of their husbands or their brothers or the sons of their brothers and the sons of their sisters or their women or their captives or male servants free of physical need or small children who have no sense of the shame of sex. They should not strike their feet in order to draw attention to their hidden ornaments. And O believers! All of you shall repent to God that you may succeed.”
As it is clearly understood from the above verse, firstly, the Holy Quran has not forbidden women to use adornments and to beautify them; in fact, it has forbidden them to display their ornaments and beautifications. Secondly, it has forbidden displaying ornaments only to non-mahram (strangers).
For further information, see:
1. Ayatollah Ahmad Mohseni Gurgani, Durr-e Naab dar Sadaf-e Hijab, Islamic Sciences Publications
2. Muhammadi Ishtihardi, Muhammad, Hijab, Indicator of Personality, 1st edition, NAJA Publications.
3. Razzaqi, Ahmad, The Factors behind Corruption and Immodesty and Methods of Combat against It, 4rth edition, Islamic Publications Organization Publications, 1992.
4. Shuja'ei, Muhammad, Durr wa Sadaf, 3rd Edition, Publication 1999.
5. Mutahhari, Murteza, The Islamic Modest Dress, Sadra Publications
6. Qira'ati, Mohsen, The Islamic Covering in Islam, 9th edition, Naser Publication, 1991
7. Javadi Amuli, Woman in the Mirror of Glory and Perfection, 2nd edition, Raja Cultural Publications, 1992.
8. Fattahi Zadeh, Fathiyah, The Islamic Modest Dress according to Quran and Sunnah (Tradition), 2nd edition, Islamic Propagations Office Publications 1997.
9. Hussein Mahdi Zadeh, “A better Understanding of Hijab” (Challenges and New Inquiries), year 81.
 - Ibn Mandur, Lisan al-Arab, the root word "Hujb".
 - Tafsir Namumah, vol.17, pg. 402; Mutahhari, Murteza, The Islamic Modest Dress, pg. 78.
 - Extracted from question 431 (site: 459) Hijab in Islam
 - Al-Noor, 30: قُلْ لِلْمُؤْمِنِينَ يَغُضُّوا مِنْ أَبْصارِهِمْ،
 - Al-Noor, 31: قُلْ لِلْمُؤْمِناتِ يَغْضُضْنَ مِنْ أَبْصارِهِنَّ،
 -- Al-Ahzab, 32: فَلا تَخْضَعْنَ بِالْقَوْلِ فَيَطْمَعَ الَّذِي فِي قَلْبِهِ مَرَضٌ
 - Al-Noor, 31 وَ لا يَضْرِبْنَ بِأَرْجُلِهِنَّ لِيُعْلَمَ ما يُخْفِينَ مِنْ زِينَتِهِنَّ
 - Extracted from “A better Understanding of Hijab” (Challenges and New Inquiries), Hussein Mahdi Zadeh.
 - Extracted from question 9, (site: 1239) Religion and Man.
 - Vide: Mutahhari, Murtaza, Collection of Works, vol.19, The Issue of Hijab, Covering the private parts (partially modified).
 - Extracted from question 825 (site: 884), The Philosophy of Women’s Hijab.
 - For further information, vide: Rott. Tronorill Kax, History of Dress, translated by Shirin Bozourgmeh; Sayyid Mahdi Qani’, “Man, clothing and Historical Roots”, Payam-e Zan Magazine, issues No. 18, 19 and 20.
 - Al-A’raf, 27: يا بَنِي آدَمَ لا يَفْتِنَنَّكُمُ الشَّيْطانُ كَما أَخْرَجَ أَبَوَيْكُمْ مِنَ الْجَنَّةِ يَنْزِعُ عَنْهُما لِباسَهُما لِيُرِيَهُما سَوْآتِهِما
 - Al-A’raf, 20: فَوَسْوَسَ لَهُمَا الشَّيْطانُ لِيُبْدِيَ لَهُما ما وُرِيَ عَنْهُما مِنْ سَوْآتِهِما
 - Al-A’raf,22: فَدَلاَّهُما بِغُرُورٍ فَلَمَّا ذاقَا الشَّجَرَةَ بَدَتْ لَهُما سَوْآتُهُما وَ طَفِقا يَخْصِفانِ عَلَيْهِما مِنْ وَرَقِ الْجَنَّةِ
 - Al-Ahzab, 33.
 - Tafsir Namunah, vol. 17, p. 290.
 - Al-A’raf, 32: قُلْ مَنْ حَرَّمَ زينَةَ اللَّهِ الَّتي أَخْرَجَ لِعِبادِهِ وَ الطَّيِّباتِ مِنَ الرِّزْقِ قُلْ هِيَ لِلَّذينَ آمَنُوا فِي الْحَياةِ الدُّنْيا خالِصَةً يَوْمَ الْقِيامَةِ كَذلِكَ نُفَصِّلُ الْآياتِ لِقَوْمٍ يَعْلَمُونَ.
 - لاينبغي للمرأة ان تعطل نفسها و لو ان تعلق في عنقها قلادة، Hurr Amili, Wasail al-Shi’ah, vol.14, Kitab al-Nikah, p. 114, hadith No. 1.
 - Go through the fatwas of a number of grand jurists in this regard: “It is haram to wear ‘fame dress’ which means a dress involving hypocrisy and pretence, a dress whose cloth or colour or sewing is not befitting for the person.” Al-Ghayah al-Quswa fi Tarjomat al-Urwat al-Wuthqa, vol.1, p. 350. “As an obligatory precaution, one should avoid wearing ‘fame dress’ which means a dress involving hypocrisy and pretence, a dress whose cloth or colour or sewing is not befitting for the person.” (Noor): It degrading and an insult to the individuals. (Fazel): What is meant by ‘fame dress’ is the dress which is, in common view, striking and which makes a person look weird; it is a dress whose cloth or colour or sewing is not befitting for the person. Tawzih al-Masail, (with annotation by Imam Khomeini), vol.1, p. 466, issue No.845.
Question 1363: Can girls wear clothes with dark blue color?
Answer: There is no problem in it by itself provided that it does not attract others’ attention or entail evils.
Question: 1363: Is it is permissible for women to wear tight and close-fitting dresses that reveal their organs? What about the transparent dresses especially those worn on weddings?
Answer: If they are not seen by strangers (non-mahram) and wearing such clothes does not entail any evil, there is no problem, otherwise it is not permissible.
Question: Is it permissible for a faithful Muslim woman to wear shiny black clothes?
Answer: There is no problem in it except for when its color and style may attract the attention or when it makes a person look outstanding. Questions asked from the Supreme Leader, Ayatollah Sayyid Ali Khamenei (may Allah grant him long life). Tawzih al-Masail (with annotation by Imam Khomeini), vol.2, p. 1012.
 - النظر سهم من سهام ابليس مسموم كم من نظرة اورثت حسرة طويلة Muhammad bin Ya’qub bin Kulayni, Furu’ Kafi, vol.5, Kitab al-Nikah, p. 559, hadith 12.
 - Verse 31 of Chapter al-Noor:
و قل للمؤمنات یغضضن من ابصارهن و یحفظن فروجهن و لایبدین زینتهن الا ما ظهر منها و لیضربن بخمرهن علی جیوبهن و لایبدین زینتهن الا لبعولتهن او آبائهن او آباء بعولتهن او ابنائهن او ابناء بعولتهن او اخوانهن او بنی اخوانهن او بنی اخواتهن او نسائهن او ما ملکت ایمانهن او التابعین غیر اولی الاربة من الرجال او الطفل الذین لم یظهروا علی عورات النساء، و لا یضربن بارجلهن لیعلم ما یخفین من زینتهن و توبوا الی الله جمیعا ایها المؤمنون لعلکم تفلحون.