Describing how he feels about his new fiancée Kenzie Dalton, One Tree Hill star Chad Michael Murray chooses to speak metaphorically. "Imagine you are walking along," he says, "and you trip over something and you turn around and find that it is a huge diamond. You would pick it up and do everything in your power to take care of that diamond because it might take care of you for the rest of your life."

It is perhaps not surprising that Murray, 24, has diamonds on his mind: He just presented Dalton, 18, a Wilmington, N.C., high school senior, with an elegant oval-cut diamond engagement ring estimated to be worth between $25,000 and $35,000. Dalton, a Tree extra whom castmates first publicly spotted with Murray last August, was seen wearing the rock last week at the state's 59th Annual Azalea Festival.

Given the speed of their engagement—just one year after Murray wed Tree costar Sophia Bush, who separated from him last September and filed for an annulment in February on grounds of "fraud"—Internet rumors abounded that Dalton might be pregnant. "Definitely not," says Murray. They are simply "crazy for one another," says Dalton's mother, Jeannie.

Although wedding plans are yet to be made, Murray says he is determined to have a long-lasting marriage. All he wants, he says, is "to be 80 years old and to have been married for 50 years and still be soooo in love."