I recall something about duty often being waived on personal effects imported to the US when the personal effects are more than one year of age when it's part of a relocation. Unlike with personal effects (where duty is sometimes waived) , however, household effects come in duty-free. Personal effects are subject to duty. And personal effects includes jewelry.

You may want to spend some time reading this as it covers a variety of situations applicable to people who come to the US: https://www.hsdl.org/?view&did=29059