15 U.S.C. § 294

It shall be unlawful for any person, firm, corporation, or association, being a manufacturer of or wholesale or retail dealer in gold or silver jewelry or gold ware, silver goods or silverware, or for any officer, manager, director, or agent of such firm, corporation, or association to import or export or cause to be imported into or exported from the United States for the purpose of selling or disposing of the same, or to deposit or cause to be deposited in the United States mails for transmission thereby, or to deliver or cause to be delivered to any common carrier for transportation from one State, Territory, or possession of the United States, or the District of Columbia, to any other State, Territory, or possession of the United States, or to said District, in interstate commerce, or to transport or cause to be transported from one State, Territory, or possession of the United States, or from the District of Columbia, to any other State, Territory, or possession of the United States, or to said District, in interstate commerce, any article of merchandise manufactured after June 13, 1907 , and made in whole or in part of gold or silver, or any alloy of either of said metals, and having stamped, branded, engraved, or printed thereon, or upon any tag, card, or label attached thereto, or upon any box, package, cover, or wrapper in which said article is incased or inclosed, any mark or word indicating or designed or intended to indicate that the gold or silver or alloy of either of said metals in such article is of a greater degree of fineness than the actual fineness or quality of such gold, silver, or alloy, according to the standards and subject to the qualifications set forth in sections 295 and 296 of this title.