What is established among the fuqaha’ is that the ‘awrah of a woman with another woman is the area between the navel and the knee, whether the woman is her mother or sister or is not her mahram. It is not permissible for a woman to look at the area between the navel and the knee of another woman,
except in cases of necessity such as medical treatment and the like.
This does not mean that a woman may sit among other women with all of her body uncovered except the area between the navel and the knee. No one does that except women who are promiscuous and negiligent, or immoral and evildoers. The words of the scholars, “The ‘awrah is the area between the navel and the knee” should not be misunderstood, because this does not mean that this is how women should always dress and show themselves among their sisters and friends. No wise person would accept that and it is not what the fitrah (sound human nature) calls for.
Rather the way a woman should dress among other women is in clothes that cover properly and express her modesty and dignity. She should not show anything except that which appears when she is working and serving others, such as the head, neck, forearms and feet, as we have mentioned when discussing mahrams above.
The Standing Committee for Issuing Fatwas has explained what a woman is not permitted to uncover in front of her mahrams and other women. We have quoted this in the answer to question no.
34745.
We ask Allaah to guide us and you.
And Allaah knows best.
Islam Q&A
~Link:
http://islamqa.info/en/ref/82994
Hope I helped!