Is a divorced woman whose husband took her jewelry entitled to file a decisive oath lawsuit to reclaim it?

There is no sin upon you for suing your husband if he takes your right. The permissibility of this is evidenced by the complaint of Hind bint Utbah about her husband, and Fatimah bint Qays concerning maintenance. You are permitted to swear an oath truthfully regarding your right if the court requests it; indeed, it is permissible to swear an oath even without being prompted.

It should be known that the husband has no right to what the wife owns, and it is not permissible for him to take it unless she offers it to him for khul' (divorce at her initiation) or gifts it to him. If the gold was part of the mahr (dowry) and he divorced her after consummation, he has no right to it. If it was before consummation, he has the right to half of it. If it was a gift, she owned it by possession. If he claims he gave it to her for adornment and retained ownership, he has the right to reclaim it if he proves that; otherwise, the default is that it belongs to the woman.