Praise be to Allah.
The husband has to realize that he is responsible for his wife, sons and daughters. According to the hadeeth of ‘Abd-Allaah ibn ‘Umar (may Allaah be pleased with them both), he said, “I heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say, Each of you is a shepherd and each of you is responsible for his flock. The ruler is a shepherd and is responsible for his flock. A man is a shepherd and is responsible for his flock. A woman is the shepherd of her husband’s household and is responsible for her flock. The servant is the shepherd of his master’s wealth and is responsible for his flock. A man is the shepherd of his father’s wealth and is responsible for his flock. Each of you is a shepherd and is responsible for his flock.”
Narrated by al-Bukhaari, 893; Muslim, 1829
So the husband will be accountable before Allaah on the Day of Resurrection for his wife and children if he fell short in advising them and teaching them properly.
The scholars have stated that women’s adornments fall into two categories:
Visible adornment, which is the woman’s outer dress
And hidden adornment, which no one should see except the husband, such as kohl, bangles and rings.
The evidence for that is the report narrated from Ibn Mas’ood (may Allaah be pleased with him) concerning the interpretation of the verse in which Allaah says (interpretation of the meaning):
“and not to show off their adornment except only that which is apparent”
Ibn Mas’ood said: The adornment is of two types, visible adornment and hidden adornment which no one should see except the husband. With regard to the visible adornment, this is the dress. With regard to the hidden adornment, this is things such as kohl, bangles and rings.
According to another report, visible adornment includes clothes. That which is hidden includes anklets, earrings and bangles.
Narrated by Ibn Jareer in his Tafseer, 18/117
A similar interpretation was also narrated from Ibn ‘Abbaas.
See Adwa’ al-Bayaan, 6/196
Therefore the scholars have said that it is obligatory for a woman to cover her face, hands and hidden adornments. This is what is regarded as more correct by a number of the scholars, including Shaykh al-Islam Ibn Taymiyah.
Al-Shanqeeti (may Allaah have mercy on him) said, when discussing this issue and after quoting the views of the scholars and stating that the report narrated from Ibn Mas’ood is more likely to be correct -:
This view is the most correct opinion in our view; it is more on the safe side, farthest removed from suspicion and causes of fitnah.
Adwa’ al-Bayaan, 6/192
Make-up and the like, and henna, are kinds of adornment which it is not permissible for a Muslim woman to show to non-mahrams.
Shaykh Muhammad al-Saalih al-‘Uthaymeen said:
There is nothing wrong with using henna for adornment, especially for a married woman who adorns herself with it for her husband. As for unmarried women, the correct view is that it is permissible, but she should not show it to people because it is a kind of adornment.
Fataawa al-Mar’ah al-Muslimah, 1/477
But some doctors have said that using artificial make-up harms a woman’s skin. If this is proven then it should be avoided.
Shaykh Ibn ‘Uthaymeen said:
If make-up beautifies a woman and does not cause her any harm, then there is nothing wrong with it, but I have heard that make-up damages the skin of the face, and that it therefore alters the skin of the face in an ugly way before the time when the skin changes as a result of ageing. I hope that women will ask their doctors about that. If that is proven, then using make-up is either haraam or makrooh at least, because everything that causes deformity in a person or makes him ugly is either haraam or makrooh.
Fataawa al-Mar’ah al-Muslimah, 1/474
With regard to a woman’s neck and ears showing from under her khimaar, this is haraam, The ears and neck are among the areas which a woman is commanded to conceal from non-mahram men; they are part of the beauty which it is forbidden to uncover in front of anyone except one's husband and mahrams.
The fuqaha’ are agreed that a woman’s ears are ‘awrah and it is not permissible to show them to non-mahrams.
Any kind of adornment that is connected to them – such as earrings – is also part of the hidden adornment which it is not permissible to show.
Al-Mawsoo’ah al-Fiqhiyyah, 2/376
Concerning the conditions of hijaab, see question no. 6991.
To sum up:
It is not permissible for a husband to allow his wife to show her hidden adornments. He must tell her to wear proper hijaab otherwise the husband will be included among those whom sharee’ah counts as not having the proper protective jealousy concerning their honour.
The Prophet (peace and blessings of Allaah be upon him) said: “There are three who will not enter Paradise and Allaah will not look at them on the Day of Resurrection: the one who disobeys his parents, the woman who imitates men, and the cuckold.”
(Narrated by Ahmad; Ahmad Shaakir (6180) said, its isnaad is saheeh).
His wife has to fear Allaah and observe proper hijaab. That will be good for her with regard to her religious commitment and before her Lord.
And Allaah knows best.