Can I go to jail

Depend if you knew it was a fake when you sold it, also your location.

The bracelet was stampd 14k italy and that's what I went by. I live in cape coral Florida

So what now makes you think it's a fake?

You may if you represented it falsely, have to give them their money back.

If you were not sure, you merely tell them the markings, not promise it is anything. But if they believe you knew it was not, and intended to cheat them, yes they could press charges against you

He called me and found out it was I didn't know I was going by what it said on the bracelet

Hello f:

If this guy goes to the cops, the cops will tell him to sue you. They'd be interested if they thought you did this for a living, but because you sold ONE piece of jewellery, they're not.

Therefore, the only recourse this guy has is in court, and even there he'll have to PROVE you KNEW it wasn't real.. That's going to be hard to do.

If this guy contacts you again, tell him POLITELY, that you didn't cheat him, and that you're NOT going to give him his money back.

excon

...
If this guy goes to the cops, the cops will tell him to sue you. ...

Agreed. It's a civil matter. If Florida makes it a crime (extremely doubtful), the authorities would find proof beyond a reasonable doubt of scienter (knowledge that it is fake) almost impossible.

In civil court, the general rule is caveat emptor.