This is a hard question to answer.
Honesty is a important, no dough in that. But honesty walks a thin line.
In my case, this is what I would do.
If I were to find a piece of jewelry that was expensive, I would check to see if there was anything engraved on it. If the item was worth over say $500.00, I would contact the police department to see if anything was reported lost.
I think other things to consider is how tarnished the object is and how deep it was.
Also like others here have said. The item may have been stolen or again, if you think it's been there awhile, and it is an expensive item, the person who lost it may have had it insured and received a settlement on the item. In that case, rather than return it to the person who lost it, you may have to check to see if an insurance claim was file and rewarded for the lost item. You may have to give it to the insurance company. I don't know legally if the insurance company could hold your responsible if a claim for the item was paid to the person who lost the item and found you had returned the item to the person instead of the insurance company. I am sure the person you returned it to wouldn't contacted the insurance company and tell them the item was found.
Anyone in this forum practice law? Would your be able to answer that question?
I figure. If you find the jewelry and it's less than $500.00, doesn't have anything engraved on it, looks like it's been in the ground awhile, it's yours! You did the work to find it, and retrieve it on your personal time. If your didn't find and retrieve the object, it would have stayed there. Maybe forever.
To bad, so sad.
Expensive stuff? Historic finds? Well, then report it to your local police department or historic socially.
I'm sorry if anyone thinks I am greedy. I am not. I am an honest man, but I believe that we dirt diggers deserve to keep some, or most of the stuff we find. We do all the work, remove trash, respect the earth and if it wasn't for us, most of the treasures would probably stay in the ground for many, many years.
I guess you have to DIG
into your moral interpretation and do what you think is right.
Good hunting.