In a Lousiana case, plaintiff alleged that he gave the ring to defendant, to whom he was engaged to be married, in consideration of their future marriage.  The marriage was never consummated.[1]  The court held that under La. Civ. Code Ann. arts. 1740, 1897, plaintiff was entitled to recover the engagement ring because there was a failure of the essential condition on which the gift was made when the engagement was broken.

[1] Wardlaw v. Conrad, 18 La. App. 387 (La.App. 1931)