Commercial imports of diamonds, jewelry, pearls, and precious and semi-precious stones valued at $2,500 or more require a formal entry. Please see the guidelines for formal entries in our publication entitled “Importing Into the United States”.
A license is not required to import these items for commercial purposes; however, a Customs bond CBP Form 301 is required for all formal entries. You can obtain a bond from a surety company. See a list of certified companies on the Bureau of the Fiscal Service website. You may also want to consider hiring a Custom Broker to file your entries on your behalf. A list of Customs Brokers in your area can be obtained on the cbp.gov website.
The Patriot Act also establishes requirements for dealers in gems and precious metals. The Financial Center is the agency responsible for developing regulations regarding registration and compliance programs.
Personal imports of these items are usually cleared informally and do not require a Customs bond. However, if you purchased them while you were abroad, ensure you declare them when clearing Customs and Border Protection (CBP) on the CBP Form 6059B. Imports of diamonds, pearls, rubies, sapphires and emeralds from countries with normal trade relation status are duty-free as long as they are not permanently strung, set or mounted. Additional duty rates for these items can be found in the Harmonized Tariff Schedule (HTS) in chapter 71.
When these items are set or mounted with some sort of metal, they are classified as jewelry and subject to duty. These rates can also be found in chapter 71. Diamonds also require a Kimberley Certificate; more information can be found on the U.S. Department of State website.
Please be aware that there are sanctions against diamonds imported from Sierra Leone, Angola, Liberia and other countries.
Source: U.S. Customs and Border Protection