ISO 18323 is the international standard published by the International Organization for Standardization that prescribes the consumer-confidence terminology and disclosure language for the diamond industry. Published in 2015 by ISO Technical Committee 174 (Jewellery), the standard codifies the language that the trade may use to describe natural diamonds, laboratory-grown diamonds, treated diamonds, and diamond simulants, in retail and trade documentation. ISO 18323 has become a touchstone reference in the global debate over disclosure and the labelling of synthetic and treated stones.

Key provisions

The standard establishes that the unqualified term diamond, used without modifier, refers to a natural diamond. It defines the acceptable adjectives and qualifiers for laboratory-grown diamonds, requiring the use of one of three terms: laboratory-grown, laboratory-created, or synthetic. The use of any other modifier such as cultured, real, genuine, or any term implying natural origin in connection with a laboratory-grown stone is prohibited under the standard. The descriptor must appear unambiguously and prominently in any retail communication.

For diamond simulants, the standard requires the use of the explicit material name (cubic zirconia, moissanite, white sapphire, glass, etc.) rather than the term diamond with any qualifier, since simulants are not diamond at all. For treated diamonds, the standard requires disclosure of the type of treatment, including HPHT (high pressure-high temperature) treatment, irradiation, fracture filling, laser drilling, and surface coating, with the disclosure language matching the actual treatment applied.

Adoption

ISO 18323 has been incorporated into the disclosure standards of the major trade bodies, including CIBJO (the World Jewellery Confederation), the Diamond Producers Association (now the Natural Diamond Council), the World Diamond Council, the Federation for the Worldwide Jewellery Community, and the principal national jewellery trade associations including AGTA in the United States and the British Jewellers' Association in the United Kingdom. The major laboratories, including GIA, IGI, HRD, and the Swiss Gemmological Institute, follow ISO 18323-aligned terminology on their reports.

The Federal Trade Commission's revised Jewelry Guides (issued 2018) brought United States consumer-protection rules broadly into alignment with ISO 18323 on synthetic disclosure, although with some specific differences in language permitted under FTC rules. European Union national consumer-protection authorities apply rules harmonised with ISO 18323. India's Bureau of Indian Standards has aligned IS 1417 and IS 2112 with ISO 18323 in its most recent revisions.

Trade significance

The widespread adoption of ISO 18323 has been one of the most consequential developments in diamond disclosure of the past decade. The standard provides clear and consistent language across markets, narrowing the room for ambiguous terms such as cultured diamond that previously created confusion at the retail level. For the working trade, the practical consequence is that disclosure language used in retail tags, online listings, and laboratory reports should be selected from the ISO 18323-permitted vocabulary, and any retail listing that uses prohibited terms exposes the seller to trade-association sanction or, in some jurisdictions, statutory consumer-protection enforcement.