This story doesn't pass the smell test. Not the Julio Jones thing, the thing about the divers not telling him they found it.
Let me get this straight. Julio wears expensive diamond stud earring. Rides Jet Ski around lake. Finds stud is missing. Ok, got it.
Julio hired divers to find stud. Okay, it's his money.
Then a report of diver buying fiance "$150,000" ring.
Right. Tell you guys what. I'll ride a Jet Ski around Lake Murray a while. At some point I'll drop a ceramic (so you can't use a metal detector) marble off the Jet Ski.
Then I'll come back to where you are waiting with your crack team of divers. I'll give you guys a general idea (to the best of my abilities, cough*) idea of where I rode around.
Let's see how long it takes to find that marble.
Only way it could ever happen is if it had a gold setting or something. Metal detectors work best with ferrous metals, but will pick up things like gold as well (this is actually kind of complicated). But there won't be much metal in that setting, and nothing like this works well with 5 to 10 feet of water or whatever. Then there is the "needle in a haystack" thing.
Not buying it unless there is more to this story.