Praise be to Allaah.
There is nothing wrong with a woman - whose parents previously did some piercings on her body or who did that to herself when she was an adult, before she became Muslim or after she became Muslim - using these piercings to wear some adornments of gold or silver or otherwise, but that is restricted to two important conditions:
That she should not show this adornment to any non-mahrams and should show it only to her husband or mahrams if it is in places where it is permissible for them to see it, such as the ear and nose for example.
That her wearing adornment in these places should not be an imitation of the kuffaar or of evildoers and immoral people. If wearing adornment in the belly button is a prevalent custom in some society among women, then there is nothing wrong with using this kind of adornment. But if it is only known among immoral women, evildoers and kuffaar, then it is not permissible to adopt this custom because that is imitating them, and imitating evildoers is not allowed.
With regard to the ruling on doing body piercing, i.e., piercing various parts of the body in order to wear adornments, the ruling on this action is subject to further discussion:
If having the piercing done involves uncovering the awrah and having a stranger or non-mahram, male or female, look at it, then this is undoubtedly a haraam action. The evil of uncovering the awrah is greater than any benefit in wearing adornments, because uncovering the awrah is one of the things that are definitively forbidden in our religion. And what uncovering it leads to of uncovering the awrah and transgressing human dignity and the temptation to commit sin is much more serious than achieving the purpose of adornment which may be achieved by simply wearing earrings, for example.
If the piercing will have an adverse effect on one's health, whether immediately or in the future, then it is haraam and it is not permissible to do it on any part of the body. We have already explained on our website some of the negative effects that result from wearing piercings in the lip or tongue. See the answer to question no. 107196.
Moreover, if the piercing of a specific part of the body is a custom among kaafirs, evildoers, promiscuous people and sinners, it is not permissible to imitate them. The Prophet (blessings and peace of Allah be upon him) said: Whoever imitates a people is one of them. Narrated by Abu Dawood, 4031; classed as hasan by al-Haafiz Ibn Hajar in Fath al-Baari, 10/282.
It is also haraam for a man to have piercings on any part of his body, because that is imitating women. It was narrated from Ibn Abbaas (may Allah be pleased with him) that the Prophet (blessings and peace of Allah be upon him) cursed effeminate men and women who imitate men and he said: Expel them from your houses. Narrated by al-Bukhaari, 5885. Ibn Aabideen (may Allah have mercy on him) said: Piercing the ear in order to wear earrings is part of the adornment of women and it is not permissible for males. End quote from Radd al-Muhtaar, 6/420
If the piercing is free of all the reservations mentioned above, then the ruling is that it is permissible in any part of the body, if adorning that part is a well known custom in that society, because the basic principle is that it is permissible for women to adorn themselves, and there is some evidence to indicate that it is permissible to pierce the ears of a little girl to put earrings, and by analogy it is permissible to pierce other parts so long as they do not include the reservations mentioned above. Moreover, the Hanafi and Hanbali fuqaha' stated that some kinds of piercing for the purpose of adornment are permissible.
It says in Radd al-Muhtaar (6/420), quoting from some books:
If it - meaning the ring in the nose - is something with which women adorn themselves, as is the case in some countries, then it is like piercing the ears - i.e., in terms of it being permissible. And the Shaafais stated that it is permissible. End quote.
See also the answer to questions no. 78255 and 103996
And Allah knows best.