Lab-grown diamond disclosure is governed in the United States by the Federal Trade Commission's Guides for the Jewelry, Precious Metals, and Pewter Industries, with the operative provisions in 16 CFR Part 23. The Guides were substantially revised in 2018 to address synthetic diamond.

Permitted terms

The 2018 Guides removed natural from the FTC's definition of diamond and permit a lab-grown stone to be described as a diamond provided the synthetic origin is clearly and conspicuously disclosed. The acceptable qualifiers, listed in Section 23.25, are laboratory-grown, laboratory-created, [manufacturer name]-created, and any other word or phrase of like meaning. Cultured may be used only if accompanied by one of the foregoing qualifiers in equally conspicuous form. Synthetic remains acceptable but is no longer required.

The qualifier must appear immediately preceding the word diamond and in equal conspicuousness to the rest of the description. Use of real, genuine, natural or precious to describe a lab-grown stone, or use of diamond unqualified in any context where confusion with a natural stone is reasonably possible, is treated as deceptive.

International framework

The CIBJO Diamond Book, ISO standard 18323 published in 2015 and updated since, and the World Federation of Diamond Bourses rules all require comparable disclosure. ISO 18323 specifies the term laboratory-grown or laboratory-created, with synthetic permitted, and prohibits use of cultured without qualifier. India's Bureau of Indian Standards and the Gem and Jewellery Export Promotion Council follow CIBJO terminology.

Practical compliance

Compliance touches every stage of trade. Suppliers must label invoices, certificates and inscribed girdles. Retailers must use compliant language in advertising, on price tags and in oral sales presentations. Lab-grown melee parcels should be physically segregated from natural parcels, and trade-buyers expect either a written representation that a parcel is unmixed or a screening instrument check on receipt. The major laboratories, including GIA and IGI, laser-inscribe LABORATORY-GROWN or LAB-GROWN into the girdle of every lab-grown report they issue, along with the report number, providing a permanent disclosure that travels with the stone.

The 2018 revision also clarified that the FTC sees no inherent deception in marketing lab-grown diamond as a diamond, but that the manner of marketing is what is policed. Implied or express claims that lab-grown stones share the rarity, environmental footprint or investment characteristics of natural stones are independently actionable as false advertising.