Voluntary gifts usually given to woman at the time of marriage are considered to be Stridhan.
The legislature has duly recognised the concept of “Stridhan” and has accordingly engrafted Section 14 of the Hindu Succession Act, 1956 which states that property of a female Hindu to be her absolute property.
Your query suggests that certain jewellery items were gifted to your wife at the time of marriage and hence, they would qualify to be considered as Stridhan and she can claim the same
Now, since your mother does not want to return them, in such an eventuality, your wife, in order to take back her Stridhan, may resort to following remedies:
(i) Move an appropriate Criminal Complaint under Section 406 of the Indian Penal Code, 1860 against your mother for committing the offence of Criminal breach of Trust before the concerned Police Station.
(ii) File a Complaint under Section 12, 18 and 19 of the Protection of Women from Domestic Violence Act, 2005 before the Court of Magistrate against your mother.
Under Section 19(8) of the Protection of Women from Domestic Violence Act, 2005, the Magistrate has the power to direct the respondent to return to the possession of the aggrieved person her stridhan or any other property or valuable security to which she is entitled to.
Under Section 18(e) of the Protection of Women from Domestic Violence Act, 2005, the Magistrate has the power to pass a protection order in favour of the aggrieved person and prohibit the respondent from “alienating any assets, operating bank lockers or bank accounts used or held or enjoyed by both the parties, jointly by the aggrieved person and the respondent or singly by the respondent, including her stridhan or any other property held either jointly by the parties or separately by them without the leave of the Magistrate”.