Praise be to Allah.
It is permissible for women to wear gold jewellery according to what is customary in their own society, because of the report narrated by Ibn Majah (3595) from ‘Ali ibn Abi Talib (may Allah be pleased with him), who said: The Messenger of Allah (blessings and peace of Allah be upon him) took hold of some silk in his left hand and some gold in his right, then he raised his hands and said: “These are forbidden for the males of my ummah, and permitted for the females.” Classed as sahih by al-Albani in Sahih Ibn Majah.
Wearing a belly button ring is permissible subject to the following conditions:
1. It should not be a symbol that is unique to any group of disbelieving women.
2. It should not be visible to anyone except the husband.
3. It should not cause any harm.
4. Wearing gold in this manner should be customary among women [in that country], because it is only permissible for women to wear gold as jewellery, and it is not permissible for them to use gold in whatever manner.
5. Ibn Qudamah (may Allah have mercy on him) said in al-Mughni (2/325): It is permissible for women to wear jewellery of gold, silver and gemstones in whatever manner is customary for them to wear it, such as bracelets, anklets, earrings and rings, and what they wear on their faces, necks, arms, legs, ears and so on. As that which it is not customary for them to wear, such as on the waist and other things that are like the jewellery of men, that is haram, just as it is haram for a man to wear women’s jewellery. End quote.
Shaykh Muhammad as-Salih al-‘Uthaymin (may Allah have mercy on him) was asked about the ruling on piercing the ears or nose of a girl for the purpose of wearing adornment.
He replied: The correct view is that there is nothing wrong with piercing the ear, because this is one of the ways of wearing permissible jewellery, and it is proven that the wives of the Companions had earrings that they would wear in their ears. The pain caused is slight, and if the ears are pierced when the girl is small, they will heal quickly.
As for piercing the nose, I do not remember any of the scholars discussing it, but it is a kind of mutilation and distortion of the features, as far as we can tell, but others may not think that. If the woman is in a country where piercing the nose is regarded as a kind of adornment and beautification, then there is nothing wrong with piercing the nose to wear jewellery in it."( Majmu‘ Fatawa Ibn ‘Uthaymin 11/ question no. 69).
And Allah knows best.