Florida courts have held that recovery of an engagement ring by the donor is allowed if the engagement is terminated by the donee or by mutual consent of the parties.[1]  The rationale of this rule is that such presents are not absolute but are made upon the implied condition that a marriage ensues.

[1] Gill v. Shively, 320 So. 2d 415 (Fla. Dist. Ct. App. 4th Dist. 1975)