Missing Jewelry, Historical 1600's House, Metal Detect Beach, Found Art Scrapping Staten Island NYC

Went directly to a site someone claimed they lost jewelery at to try and recover it for them. The site happened to be at a historical site next to the beach. Metal detected the beach and found a good piece art on the side of the road. Perhaps it’s worth a lot?

In this house on September 11,1776 after The Battle of Long Island a peace conference was held between Lord Howe, Benjamin Franklin, John Adams, and Edward Rutledge. They rowed from New Jersey.