ISO 18323:2015, jewellery consumer confidence in the diamond industry

What ISO 18323 covers

ISO 18323:2015 covers the nomenclature, the permitted and required descriptors, for four categories of diamond-related products sold to consumers (ISO 18323:2015, iso.org/standard/62163.html):

Natural diamonds: Diamonds formed naturally in the earth. Under ISO 18323, the term "diamond" without further qualification means natural diamond. Additional qualifiers such as "mined" or "natural" may be used but are not required for natural diamonds because "diamond" is already defined as natural.

Treated diamonds: Natural diamonds that have been subjected to treatments, colour enhancement, fracture filling, laser drilling, coating, that alter their appearance. ISO 18323 requires that any significant treatment be disclosed to the consumer. The standard specifies that treated diamonds must be described in terms that make the treatment clear.

Synthetic (laboratory-grown) diamonds: The area where ISO 18323 has had the most commercial impact. The standard requires that synthetic diamonds, whether HPHT or CVD, be described using full, unambiguous terminology. Acceptable terms include "laboratory-grown diamond," "synthetic diamond," "laboratory-created diamond," or "man-made diamond." The term "cultivated diamond" or "cultured diamond" is not accepted under the standard as it creates potential confusion with cultured pearls (which are genuine pearls from living organisms).

Diamond simulants: Non-diamond materials that visually resemble diamonds (cubic zirconia, moissanite, white sapphire). These must be clearly described as simulants and must not be described as "diamonds" of any type.

The foundational rule: "diamond" = natural

The most significant single provision of ISO 18323:2015 is its definitional rule: the word "diamond" used alone, without qualification, unambiguously means a natural diamond. This rule was designed to prevent the consumer confusion that arises when laboratory-grown diamonds are marketed using the unqualified term "diamond."

The rule has practical commercial significance. A retailer who sells a laboratory-grown diamond described only as a "diamond", without the "laboratory-grown" qualifier, is in violation of ISO 18323 standards in countries where the standard has been adopted. In the United States, the FTC updated its Jewelry Guides in 2018 to incorporate similar language, reflecting the same principle as ISO 18323 (US Federal Trade Commission, "Jewelry Guides," ftc.gov, 2018). India's BIS standards for diamond jewellery labelling are similarly moving towards alignment with international nomenclature standards.

ISO 18323 and its relationship to CIBJO and ISO 24016

ISO 18323:2015 was developed using the CIBJO Diamond Blue Book and the IDC Rules as its primary source documents (CIBJO, "Industry Standards Introduction," cibjo.org/industry-standard-intro). It addresses the first layer of consumer protection, the language used to describe diamonds, but does not specify how diamonds should be graded. That second layer was addressed by ISO 24016:2020.

Together, ISO 18323 and ISO 24016 form a complete ISO framework for natural polished diamonds: 18323 governs the descriptors used in selling; 24016 governs how the stone's quality is assessed and described. CIBJO's President described the combination as meaning "the entire gemstone category of diamonds has been fully addressed by the International Standards Organisation" (CIBJO President statement, CIBJO press release on ISO 24016, September 2020, cibjo.org).

Adoption and enforcement

ISO 18323:2015 is a voluntary standard. There is no international mandatory enforcement mechanism, ISO standards are adopted voluntarily by national standards bodies and may or may not be incorporated into national law. However, the standard has been adopted by European national standards bodies (including BSI in the UK and DIN in Germany) and is referenced in CIBJO's own Blue Books, meaning industry members who follow CIBJO guidelines are aligned with ISO 18323.

In jurisdictions where the standard has been incorporated into consumer protection law or trade practice regulations, the requirements are legally binding for sellers in those markets. The 2004 German court case involving the "cultured diamonds" term, decided on the basis of CIBJO nomenclature before ISO 18323 existed, illustrates how voluntary standards become legal reference points in consumer disputes (CIBJO, "Industry Standards Introduction," cibjo.org/industry-standard-intro).

Primary sources