Oddly enough, I can answer this pretty definitavely, at least as to New York law. Several months ago, I represented a former fiance who went to trial for the return of the ring he gave his fiancee or its value.
My client won a judgment for the amount he originally paid for the ring, plus interest, or for the return of the ring. Return of the ring, however, was problematic, because she had sold it back to the jeweler for a lot less than he had originally paid.
New York Civil Rights Law Section 80-b provides:
In other words, certain gifts are considered “gifts in contemplation of marriage,” the classic example of which is an engagement ring. If the marriage does not occur, then the gift must be returned to the giver.
Her defense was that at the time the engagement broke up, he gave it to her as an outright gift. However, in order to demonstrate an outright gift, all of the elements of gift giving must be proved by “clear and convincing evidence.” The facts regarding what happened at the break-up of the engagement were unclear and disputed, to say the least.
Anyway, under New York law, a gift given in contemplation of marriage, such as an engagement ring or dowry, must be returned on the break-up of the engagement, regardless of which party, if one can be identified, broke up the engagement.