Legal Question in Family Law in California

The conduct of your wife will have little to do with ownership of the ring. The general rule is that a gift to a spouse is separate property. You would have to prove that the gift of the ring was conditioned that she remain faithful to the marriage. That will be difficult to prove. Further the court will not likely agree that the ring is hers only during the time she if faithful to the marriage. Unless the ring is very valuable or has great sentimental value it will cost more to try and obtain it than it is wortk.