Family or ansestoral ornaments given to the bride at wedding.

We are living in Germany, Europe we are Hindu Punjabi. My son got married to a Hindu Punjabi girl in Aug 2017 and after a few months he found out that the girl has an pre marital affair which she admitted to him only. They were on a holiday that time. She agreed to behave herself and the matter stopped there only. But later the boy found the same was still going on and he filed a divorce after separation of one year. in the court she denied having an affair any time. The court ordered the boy to pay alimony to hare although she earns quite a good salary herself. We paid in lump sum and the divorce went through. At the time of wedding we gave the bride our family and ancestral ornaments which belongs to my grand mother, were given to my mother, next to my wife and further to this girl. Now she is refusing to give the ornaments back. My question is - How to claim these jewels back from them ? Do they have any legal right to keep these as streedhan as per Hindu Marriage act 1955 ? Thank and best regards AA