Al Jawaab Billahit-Tawfeeq
Bismillahir Rahmaanir Raheem
It is permissible for women to wear White Gold Rings.
Please refer to this link: http://askimam.org/public/question_detail/22519
The answer is written by a dear friend of mine who is currently studying under the tutelage of Mufti Ebrahim Desai.
And Allah knows best.