You/your wife have two options which can be used:
1) File a police complaint
. The police will investigate and may charge her with theft. However, this may not result in the ring being returned, especially if she claims innocence.
2) File a civil lawsuit for conversion
(civil theft). If so, then the Court
decides. The ring can be returned, or, she can be held liable for a judgment for the worth of the ring.
Perhaps the threat to do do BOTH/EITHER would be enough to have her return it without involving the Courts.
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