In October 2004, a German court issued a restraining order against a synthetic diamond distributor that had been using the term "cultured diamonds" when marketing its products. The legal basis was CIBJO nomenclature, the Diamond Blue Book specifies that diamonds may not be described using terms that imply naturalness when they are synthetic. The court case established that CIBJO's voluntary industry standard had been incorporated into German consumer law. The same pattern has repeated in other jurisdictions: voluntary CIBJO standards become the reference for what constitutes fair dealing in diamond transactions. A document that carries no legal mandate in most markets has nonetheless become the benchmark against which legal standards are measured. : CIBJO, "Industry Standards Introduction," cibjo.org/industry-standard-intro; Rudi Biehler, CIBJO Germany, 2004 case documented in CIBJO historical records
Quick answer CIBJO (Confédération Internationale de la Bijouterie, Joaillerie et Orfèvrerie des Diamants, Perles et Pierres, the World Jewellery Confederation) is the international organisation representing the global jewellery industry. Founded in 1926 and headquartered in Milan (Viale Berengario 19, 20149), CIBJO represents national associations, trade organisations, and laboratories from across the global jewellery, gemstone, and precious metals industries. Its Blue Books, of which the Diamond Blue Book is one, are the definitive sets of grading standards and nomenclature for the industry. The Diamond Blue Book is updated annually, is a living document, and is available free at cibjo.org. The current edition is valid as of November 2024. Source: CIBJO institutional information, cibjo.org; CIBJO Diamond Blue Book 2024 edition, cibjo.org/the-blue-books.

CIBJO: the organisation behind the standard

CIBJO was founded in 1926, making it the oldest international organisation in the jewellery sector. It operates as a non-profit confederation of national and regional organisations representing members from the jewellery, gemstone, pearl, and precious metals industries across dozens of countries. Major international bodies including GIA, the Israel Diamond Exchange, the Antwerp World Diamond Centre, and national gem and jewellery associations in India, the US, Europe, and Asia are represented in CIBJO's membership structure (CIBJO institutional information, cibjo.org).

CIBJO is headquartered in Milan: Viale Berengario 19, 20149 Milano, Italy. Contact: [email protected]. Its annual Congress provides the forum for updating Blue Books and coordinating standards across the global industry.

The CIBJO Blue Books: a complete framework

CIBJO publishes six Blue Books covering the full range of the jewellery industry (CIBJO, "The Blue Books," cibjo.org/the-blue-books, 2024):

The Diamond Book · The Gemstone Book · The Pearl Book · The Coral Book · The Precious Metals Book · The Gemmological Laboratory Book · The Responsible Sourcing Book

Each Blue Book is a living document reviewed and updated annually. They are available for free download at cibjo.org to all industry participants and public users. The application of Blue Book standards is voluntary, but CIBJO recommends that they apply to all persons and organisations throughout the jewellery supply chain. In several jurisdictions, Blue Book standards have been incorporated by reference into consumer protection law, making them effectively legally binding in those markets (CIBJO, "Industry Standards Introduction," cibjo.org/industry-standard-intro).

The Diamond Blue Book: what it covers

The CIBJO Diamond Blue Book covers natural diamonds, treated diamonds, laboratory-grown diamonds, composite diamonds, and diamond simulants. Its scope includes (CIBJO Diamond Blue Book, 2024 edition, cibjo.org):

Nomenclature: Permitted and prohibited terms for describing diamonds in trade. Specifies which descriptors are acceptable for natural diamonds, which are required for lab-grown diamonds, and which terms are misleading or deceptive when used without qualification.

Grading standards: The colour grading system (D-Z scale), clarity grading system (Flawless to Included), and cut quality assessment framework used across the international diamond trade. These scales form the vocabulary that GIA, IGI, and other laboratories use in their grading reports.

Treatment disclosure: What diamond treatments must be disclosed and how. Fracture filling, HPHT colour treatment, laser drilling, and coating are all covered with specific disclosure requirements.

Laboratory-grown diamond guidelines: CIBJO published separate Laboratory-Grown Diamond (LGD) Guidelines in 2024, specifying that CVD and HPHT manufacturing processes must be disclosed on any product specification or grading report, and that the term "laboratory-grown" or equivalent must be used clearly (CIBJO LGD Guidelines, cibjo.org, 2024).

Key definitions in the CIBJO Diamond Blue Book

Several of the CIBJO Diamond Blue Book's definitions are particularly important for buyers to understand, as they determine what language is and is not acceptable in diamond marketing (CIBJO Diamond Blue Book, 2024 edition):

"Diamond" without qualification = natural: Under CIBJO standards, and under ISO 18323:2015, which references CIBJO, the word "diamond" used alone, without qualification, always means a natural diamond. A laboratory-grown diamond must be described as "laboratory-grown diamond," "synthetic diamond," or "laboratory-created diamond." Using the word "diamond" alone for a synthetic stone is a violation of CIBJO nomenclature.

Prohibited terms: CIBJO prohibits certain terms as misleading. "Cultured diamond" is prohibited (it implies natural origin by analogy with cultured pearls, which are genuine pearls). "Man-made diamond" without clear disclosure context is problematic. The term "real diamond" used to contrast a lab-grown diamond with a simulant is permitted (a lab-grown diamond is a real diamond in chemical terms) but the natural/synthetic distinction must be separately clear.

Colour grading scale: The CIBJO Diamond Blue Book defines colour grades using the D-through-L letter scale (for "colourless" through "faint yellow") and extends through M-Z for progressively more tinted stones. This is the same scale GIA uses; CIBJO and GIA developed these scales in parallel and they are consistent (CIBJO Diamond Blue Book, 2024 edition, colour grade definitions).

Clarity grading: CIBJO's clarity scale, Flawless, Internally Flawless, VVS1, VVS2, VS1, VS2, SI1, SI2, P1 (Piqué 1), P2 (Piqué 2), P3 (Piqué 3), uses "Piqué" terminology from the traditional European trade rather than GIA's "I1, I2, I3" terminology for the Included grades. In practice, SI2/P1/I1 broadly correspond across systems, but the exact grade boundary definitions vary. European-certified diamonds are more likely to use Piqué terminology (CIBJO Diamond Blue Book, 2024 edition, clarity grade definitions).

CIBJO on laboratory-grown diamonds

CIBJO published dedicated Laboratory-Grown Diamond (LGD) Guidelines in 2024 to address the rapidly growing lab-grown market. Key requirements from these guidelines (CIBJO LGD Guidelines, cibjo.org, 2024):

The manufacturing process, HPHT or CVD, must be stated on the product specification or grading report. If any post-growth treatments have been applied, these must also be disclosed. Lab-grown diamonds should be described with an "LG" prefix before clarity grades on grading documents (e.g. LG VS1, LG SI2). The grading scales for lab-grown diamonds follow the same D-Z colour and FL-I3 clarity scales as natural diamonds, with the "LG" prefix indicating the stone's origin on the grading document.

CIBJO and GIA: aligned but independent

GIA and CIBJO did not develop their standards jointly, but the standards they independently developed are closely aligned, they emerged from the same gemological community using the same scientific and practical knowledge base. The D-Z colour scale appears in both GIA's published methodology and CIBJO's Diamond Blue Book; the FL-I3 clarity scale (with the Piqué variation noted) appears in both. The reasons are historical: the gemologists who developed GIA's standards in the 1950s were part of the same international community that participated in CIBJO's standard-setting. Alignment was the natural result of a shared knowledge base rather than a formal coordination process.

When ISO developed diamond standards (ISO 18323:2015 and ISO 24016:2020), it explicitly used the CIBJO Diamond Blue Book as its primary reference document, with CIBJO granting permission to use its Publicly Available Specification PAS 1048 as a basis for drafting (CIBJO, "CIBJO describes as ground-breaking the publication of ISO 24016," cibjo.org, September 2020). ISO 24016 is described by CIBJO as "essentially paralleling" the Diamond Blue Book, meaning the ISO standard validates the Blue Book's framework rather than replacing it.

How to download the CIBJO Diamond Blue Book

The CIBJO Diamond Blue Book is available free of charge at cibjo.org/the-blue-books. Select the Diamond Book entry and download the current edition (valid November 2024 as of this writing). CIBJO's Blue Books are made available at no cost as a service to the industry and to consumers. Verify you have the current edition at the time of use, CIBJO updates the Blue Books annually and the website always carries the latest version.

Primary sources

CIBJO Diamond Blue Book (2024 edition, valid November 2024). World Jewellery Confederation (CIBJO), Viale Berengario 19, 20149 Milan, Italy. [email protected]. Available at cibjo.org/the-blue-books. [Complete diamond nomenclature and grading standards; colour and clarity scale definitions; treatment disclosure requirements.]

CIBJO Laboratory-Grown Diamond (LGD) Guidelines (2024). World Jewellery Confederation. Available at cibjo.org. [LGD disclosure requirements, "LG" prefix standard, process disclosure requirements for HPHT and CVD.]

CIBJO, "The Blue Books." cibjo.org/the-blue-books, 2024. [Overview of all six Blue Books, voluntary nature, annual review process, free download policy.]

CIBJO, "Industry Standards Introduction." cibjo.org/industry-standard-intro. [CIBJO's role in ISO standards development, 2004 German court case, Blue Books incorporated into law in some jurisdictions.]

CIBJO, "CIBJO describes as ground-breaking the publication of ISO 24016." cibjo.org, September 2020. [CIBJO President Gaetano Cavalieri's statement; ISO 24016 as validation of CIBJO Diamond Blue Book; permission for use of PAS 1048 as ISO drafting basis.]

Standards section
Overview of all standards · ISO 18323:2015 · ISO 24016:2020 · WDC System of Warranties