It is mentioned in Behisti Zewar that women are not allowed to wear rings made out of metals other than gold or silver. Assuming that I have not misread this masla, what is the daleel this masla is based on.
This is the opinion of the majority of Hanafi Jurists, even though their is
some difference of opinion in imitation rings.
This view is based on the ahadith mentioning that Nabi (sallalahu Alaihi
Wasallam) rebuked a person wearing a iron ring and said that he is wearing
the jewellery of the people of Jahannum. He threw away the ring and wore one
of brass upon which Nabi (sallalahu Alaihi Wasallam) said that the smell of
idols is emanating from it (as idols were generally made of brass). He then
asked Nabi (sallalahu Alaihi Wasallam) what ring he should wear, so Nabi
(sallalahu Alaihi Wasallam) instructed him to wear one of silver, its weight
being less than a mithqaal (4.85 grams).
Narrated by Abu Dawud Vol.4 Pg.90, Tirmizi Vol.4 Pg.248, Ibn Hibbaan Vol.12
Pg.299, Nasai Vol.8 Pg.172)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai