Eyebrow Rings: Allowed for Muslim Women?
Question

Is it permissible for a woman to put a ring in her eyebrow?
Praise be to Allah.Conditions of Women’s adornment in Islam
A Muslim woman may adorn herself with permissible things, whether that is gold or silver, or other types of jewels. 
A Muslim woman may adorn herself with them however she wants, but there are conditions for that, which include the following: 
1.      It should not be an imitation of unbelieving or immoral women.
2.      It should not be done to look weird or stand out; rather it should be done in accordance with the custom of women in her country.
3.      It should not cause any harm.
4.      It should not contain any image of animate beings.
Ibn Qudamah (may Allah have mercy on him) said: 
“It is permissible for women to adorn themselves with gold, silver and jewels according to their custom, such as bracelets, anklets , earrings and rings, and what they wear on their faces, necks, arms, ears and elsewhere. As for that which is not customary for them, such as some types of belts and the like, which is specifically for men, that is haram, as is also the case if a man were to adopt women's adornment.” (Al-Mughni, 2/325) 
Shaykh Muhammad ibn Ibrahim (may Allah have mercy on him) said: 
“Islam, in its wisdom, permits women to adorn themselves in customary manners.” (Fatawa Muhammad ibn Ibrahim, 4/73)
Ear and nose piercing in Islam
Shaykh Ibn ‘Uthaymin (may Allah have mercy on him) was asked about the ruling on piercing a girl’s ears for the purpose of adornment. 
He replied: 
“The correct view is that there is nothing wrong with piercing the ears , because this is one of the means of permissible adornment. It is proven that the women of the Sahabah had earrings that they wore in their ears, and this pain is mild; if it is done when the child is small it heals quickly. 
With regard to piercing the nose , I do not remember any of the scholars saying anything about it, but it is a kind of mutilation and deforming the features as far as we can see, but there may be others who do not agree with that. If women in a country regard putting jewellery in the nose as a kind of adornment and beautification, there is nothing wrong with piercing the nose in order to put jewellery in it.” (Majmu‘ Fatawa wa Rasail Ibn ‘Uthaymin, 11/92) 
Wearing eyebrow rings by Muslim women 
The same may be said about putting a ring in the eyebrow. If that is the custom of Muslim women in your country and it does not cause any harm, then there is nothing wrong with it. 
It should be noted that women are forbidden to show their adornment in front of non-mahram men . If she puts this ring (in her eyebrow) she should only show it in front of other women, her husband and her mahrams. 
And Allah knows best.