He posted a photograph of his ring and his story on Facebook and got a few responses, but no real leads. A friend encouraged him to keep looking, and he picked up the search again. He eventually found a marriage record that revealed that Hearst had married and become Louise Hearst Entzminger.
Census records showed she had lived near the Springs in the 1930s when it was public property and known as Sanlando Springs. Banjanin believes Hearst likely lost the ring while swimming in the spring.
With that information, he could uncover that she'd died and was buried in Bylthewood, S.C. He tracked down her grandson, John Entzminger, in Oakton, Va., and contacted him in December 2011.
"It was [Entzminger's] birthday, and I called him," Banjanin said. "He was just amazed. He's also a Christian, and we both think it was meant to be right at that time."
"I said, 'Wow I can't believe it!'" Entzminger told ABCNews.com of his reaction when Banjanin called him. "I got it on Christmas Eve. It really made a great present."
Though Banjanin has been on countless dives, he said this one was unique.
"I've found earrings -- a gold earring I got $19 for -- old coins, antique bottles, nothing really worth anything, mostly junk," Banjanin said. "I don't think I'll be able to top this one."