With this article, we would like to give more insight into the history of this working group and, more importantly, our publicly accessible Information Sheets and our most recent advancements in harmonization of nomenclature and report wording that was achieved at our latest meeting in 2025 in Basel, Switzerland.

The History and Structure of the LMHC

The LMHC was formed as a direct response to the global market’s demand for consistent reporting standards. The precursors to the LMHC were the InterGemLab Group (1986) and discussions within the GILC (Gemstone Industry & Laboratory Conference of the ICA).

The decisive move to establish the LMHC occurred after a GILC meeting in Basel in May of 2001. Kenneth Scarratt was asked by Roland Naftule and Ronny Totah to form and chair a new group of international gemological laboratories to harmonize report nomenclature.

The GILC meeting had requested this formation, specifying that the new group should be (1) exclusively composed of lab representatives, (2) with a limited number of members, and (3) working in laboratories operating on the international market.

The initial members in 2001 included Gübelin Gem Lab, GIA Gemological Institute of America, CISGEM Laboratory from Italy, SSEF Swiss Gemmological Institute, and AGTA Gemological Testing Center (GTC). The Gemmological Association of All Japan GAAJ-ZENHOKYO, and GIT Thailand joined shortly thereafter.

Today, the LMHC is comprised of representatives from seven major international gemological laboratories: the Central Gem Laboratory (CGL, Japan), CISGEM Laboratory (Italy), DSEF German Gem Lab (Germany), GIA Gem Laboratory (USA), The Gem and Jewelry Institute of Thailand (GIT, Thailand), Gübelin Gem Lab Ltd. (Switzerland), and Swiss Gemmological Institute—SSEF (Switzerland).

The LMHC strictly maintains its independence, as it does not maintain formal relationships with special interest groups or trade organizations. The committee regularly meets to discuss gemological issues and to update or add to the contents of the Information Sheets.

LMHC Standardization Activities: Information Sheets

The LMHC focuses its standardization efforts on its Information Sheets (IS), which mandate specific language for reports on complex materials and treatments.

Until today, the LMHC has published on its website (www.lmhc-gemmology.org) a total of 17 Information Sheets, most concerning report language for colored stones, one for pearls, and a general one about gemological reports. This effort is designed to create a general understanding and philosophy for proper nomenclature and disclosure for gem laboratories and to suggest “preferable” language to be used in the gemstone and pearl trade.

LMHC Information Sheet, in Short

0: Gemmological Laboratory Reports. This Information Sheet provides essential overarching guidance regarding the content and legal claims of gemological reports.

1: Corundum with Residues from the Heating Process. It standardizes the nomenclature used to describe heat treatment in corundum where a degree of healing along fissures has occurred and residues from the heating process remain within healed fissures and cavities.

2: Corundum – Lattice diffusion of foreign elements other than hydrogen. This document standardizes the nomenclature for corundum that shows indications of heating accompanied by diffusion of a chemical element(s) from an external source to modify or create color.

3: Corundum with Glass-Filled Fissures and Cavities. This Sheet standardizes the nomenclature for corundum where the clarity has been enhanced/modified by the filling of fissures and/or cavities with glass. This treatment usually applies to low quality stones.

4: Corundum – Padparadscha sapphire. It defines a padparadscha sapphire as a variety of corundum from any geographical origin whose overall color appearance is a subtle mixture of pinkish orange to orangey pink with pastel tones and low to medium saturation when viewed in standard daylight. For any corundum of padparadscha-like color, a color stability test is mandatory (see Information Sheet No. 16).

5: Emerald. This Sheet standardizes nomenclature for emerald, defined as a beryl mainly colored by chromium and/or vanadium showing medium to strong green saturation. It provides standardized report wording for fissure filling and cavity filling using colorless to near-colorless oils, resins, or wax.

6: Paraiba Tourmaline. It defines Paraíba tourmaline as a blue, bluish green to greenish blue, green, or yellowish green tourmaline, mainly colored due to the presence of copper (Cu) and manganese (Mn) of whatever geographical origin.

7: Corundum – No indications of heating / Indications of heating. This Sheet standardizes the reporting of corundum that shows “no indications of heating (NH).”

8: Gemstones Where Color Authenticity is Undeter-mined. It addresses gemstones that are commonly heated and/or irradiated, but where treatment is typically not determinable, and how this should be addressed on reports.

9: Description of Color-Change in Gemstones. It standardizes the definition of color-change (main hue in standardized daylight differs from that in standard incandescent light). Alexandrite is defined as a chromium-bearing variety of chrysoberyl showing a color-change, typically from a “cold” hue (e.g., greenish) in daylight to a “warm” hue (e.g., reddish-purplish) in incandescent light.

10: Amber and Copal. This Sheet standardizes the nomenclature for natural fossilised resin (amber) and sub-fossilised resin (copal) showing indications of heating, with or without pressure.

11: Jade and Related Materials. This updated Sheet clarifies that Jade is a trade name that encompasses aggregates primarily composed of nephrite, jadeite, omphacite, or kosmochlor. The sheet includes a definition for Fei Cui, a historic Chinese name for a structurally tough ornamental aggregate composed solely or principally of any combination of jadeite, omphacite, and kosmochlor. It standardizes the classifi-cation of treated pyroxene jades using trade terms like ‘A-jade’ (no impregnation), ‘B-jade’ (bleached and impregnated), ‘C-jade’ (dyed), and ‘B+C-jade’ (dyed and impregnated).

12: Organic Fillers (Oil, Resin, Wax) in Gemstones. This Sheet standardizes nomenclature for the use of colorless or near colorless organic fillers (oil, resin, wax) in fissures, fractures, and/or cavities of any gemstone.

13: Hydrophane Opal. This Sheet defines hydrophane opal as opal that absorbs liquids to the point of affecting its appearance and potentially its weight due to considerable porosity.

14: Cobalt Spinel. This new Information Sheet stan-dardizes nomenclature for blue spinel containing traces of cobalt.

15: Tanzanite. This new Information Sheet standard-izes terminology for Tanzanite, defining it as the vanadium-bearing blue to purple color variety of the mineral zoisite.

16: Color Stability Testing of Gemstones. This new Information Sheet standardizes the method used to test the color stability of gemstones.

And finally,
Pearl Information Sheet #1: Submissions Containing Multiple Natural and/or Cultured Pearls. This Sheet standardizes the examination policies and the report wording to describe natural and cultured pearls when strung in strands, necklaces, bunches, or lots.

Updates and New Information Sheets in 2025

At the latest meeting of the LMHC working group in Basel in May 2025, significant progress was achieved and new Information Sheets (IS#14 – #16) and updates on existing Information Sheets were drafted and finally approved in October 2025 by all LMHC group members.

The most important topic of discussion and harmoniza-tion was about the color stability testing of gemstones (see new IS#16). The new information sheet stan-dardizes the method used to test the color stability of gemstones. It addresses issues where certain color centers are unstable, potentially resulting in the fading or shifting of a gemstone’s color following prolonged exposure to daylight. This phenomenon is specifically observed in certain padparadscha sapphires, fancy sapphires, spodumene, sodalite, or zircon.

The harmonized testing method involves three main steps: (1) careful initial color grading, (2) exposure to a strong light source for a minimum of three hours to examine for “deactivation”, and (3) subsequent color grading. An activation test using UV light is also suggested to check if the color instability is reversible (reversible photochromism or tenebrescence). As such, this testing method is even applicable by any member of the trade and not necessarily requires lab equipment.

Further additions included a new Information Sheet about cobalt spinel (IS#14) and tanzanite (IS#15). The committee also finalized significant updates to LMHC Information Sheet #11 (Jade and Related Materials) and IS#13 (Hydrophane Opal), including easy-to-use methods to separate opal from hydrophane opal.

The Importance of Collaboration and Consumer Confidence

The LMHC’s ongoing work, including the recent unanimous approval of the three new Information Sheets (IS #14, #15, #16) and significant updates to IS#11 and #13, underscores the committee’s commitment to scientific rigor and market transparency. The collective ownership of the LMHC documents, with rights jointly reserved by all seven member laboratories, highlights the essential nature of collaboration between labs.

We are convinced that a harmonization of report language directly serves the interests of the entire gemstone trade. By ensuring consistency and clarity in gemological lab reports, the LMHC establishes a shared language that allows dealers, manufacturers, and retailers to transact based on objective, scientific terminology. Ultimately, the LMHC’s efforts are essential for safeguarding consumer confidence in gemstones, as it was the vision 25 years ago when this working group was initiated by the trade.

The LMHC encourages all members of the trade to consult the new and updated Information Sheets on their official website: www.lmhc-gemmology.org

Authors’ Affiliations

¹Swiss Gemmological Institute SSEF, Basel, Switzerland, michael.krzemnicki@ssef.ch;
²Department of Environmental Sciences, University of Basel, Switzerland;
³Faculty of Geosciences and Environment, University of Lausanne, Switzerland;
⁴DSEF German Gem Lab;
⁵Central Gemmological Laboratory, CGL, Japan;
⁶Gemological Institute of America, GIA, USA;
⁷Gübelin Gem Lab, Lucerne, Switzerland;
⁸Gem and Jewelry Institute of Thailand, GIT, Bangkok, Thailand;
⁹CISGEM Laboratory, Milan, Italy.

All images are courtesy of LMHC.

The post The Laboratory Manual Harmonisation Committee (LMHC) appeared first on Incolor Magazine.

As the demand for precious corals continues to grow, particularly in markets like Asia, so too do conservation concerns for precious corals. Since 2008 (at the request of China), imports and exports of several precious coral species, including Corallium elatius, Pleurocorallium japonicum, Pleurocorallium konojoi, and Pleurocorallium secundum, require CITES Appendix-III documentation.

Appendix III coverage is applied at the request of a specific country (in this case, China). Significantly, Corallium rubrum, the Mediterranean coral which is the oldest and most commonly known variety of coral used in jewelry, is the only major precious coral species not covered by CITES.

In 2015, CIBJO (the World Jewellery Confederation) established a coral com-mission and released the first coral Blue Book covering the terminology and education on precious corals.

These precious corals embody a millennial tradition. Often fished at great depths, there are many scientific secrets still to be unravelled about them.

With the current advancements in genetic techniques and gemological testing, it now seems a good time to examine the progress being made by science to accurately identify these precious gems.

The Biology of Precious Coral

Corals are formed by compact colonies of many individual polyps. These polyps secrete calcium carbonate to create a hard skeletal structure that offers them shelter and structure. The material utilized in jewelry is, in fact, the hard coral skeleton itself. Similarly to pearls, precious coral is thus a product of biomineralization. Unlike reef corals that live in shallow depths, precious corals are found in much greater depths (generally 50-1500m) in the Mediterranean, Asia, and the Pacific.

While Corallium rubrum (Mediterranean red coral) was historically found at shallower depths, overfishing in recent centuries has led to a reduction in these shallow populations.

Efforts to protect these remaining communities have been incorporated into recent GFCM (General Fisheries Com-mission for the Mediterranean) rules, which now prohibit coral harvesting at depths of less than 50 meters.

The deep-sea environment of most precious corals dictates an extremely slow rate of growth for these species. Due to this exceptionally slow growth, it is challenging to cultivate precious corals in a way that is commercially feasible.

Species and the Spectrum of Trade

Of the thousands of coral species existing in the ocean, only a very small number can and have been used in jewelry. These are the ones called precious corals and varieties include red, pink, orange, and white types, all belonging to the family Coralliidae.

The main species found in the jewelry trade, alongside their distribution and traditional market names, demonstrate the complex taxonomy of these gems.

The Importance of Regulations and CITES

Protecting precious coral species involves two primary levels of regulation. The first involves regulating fishing practices within the source regions, including the Mediterranean, Japan, Taiwan, and China.

The second level is regulation at the trading stage through the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which entered into force in 1975 to address concerns that global trade was endangering numerous species.

Because only certain species are listed by CITES, it is imperative that species are identified correctly. This has traditionally been done on a visual basis by dealers and customs agents, but visual identification has its limitations.

Because many precious coral species share very similar characteristics and colors, traditional gemological techniques often fail to tell them apart. However, by reading their genetic fingerprints, it is possible to identify different species unambiguously. This allows for greater transparency and enables the further documentation of the provenance of both historic and modern precious coral jewels.

DNA Testing: A New Era of Identification

A significant step forward in coral species identification occurred in May 2020 with the publication of a study in the journal Scientific Reports. The paper, entitled “DNA fingerprinting: an effective tool for taxonomic identification of precious corals in jewellery,” detailed a methodology to conclusively identify a precious coral species.

This 2020 research marked the first major scientific study to describe a technique capable of using minute amounts of DNA recovered from precious coral used in jewelry to accurately identify the species. Crucially, the technique is considered quasi non-destructive and requires significantly less sample material than other analytical methods, with testable DNA successfully recovered from as little as 2.3 milligrams (0.0115 carats) of material.

One of the main findings was the discovery of a new species, Pleurocorallium niveum (originating in the Pacific), which had never previously been reported in the jewelry industry but was identified in several submitted coral cabochons. This finding underscored that there is still much to learn scientifically about precious corals.

In 2022, another study (published in Forensic Science International: Genetics) presented the Coral-ID method that was tested on a real-world set of samples, comprised of 20 coral-set items seized between 2009 and 2017 by the Swiss customs authorities, because they lacked valid CITES documentation.

Three of the 20 tested samples were shown to be from species that have not previously been associated with precious coral in the jewelry trade. This further underscored the need for additional scientific research.

This led to the latest research published earlier this year in two peer-reviewed journals—one in Coral Reefs and one in Diversity. The Coral Reefs study ad-dressed existing taxonomic uncertainties, specifically regarding the CITES-listed species Pleurocorallium secundum. We revisited the 1840s holotype of this species (a holotype is the official “reference specimen” for a species), which is housed at the Smithsonian National Museum of Natural History in Washington D.C.. By employing low-copy DNA analysis, the study provided genetic transparency and confirmed that the
original and subsequently identified specimens are indeed the same species.

The second paper, published in Diversity, focused on a rare angel’s skin (see image above) necklace that was submitted to the SSEF lab. Angel’s skin precious coral material is highly valued for its delicate light-pink hue and can command top-market prices.

DNA fingerprinting conclusively demonstrated that the material did not match either of the two species that might have been visually assumed to match with this type of material (Pleurocorallium elatius or Pleurocorallium secundum).

Instead, the material matched a newly identified precious coral species hitherto unknown both in the precious coral trade and to gemmologists. It was identified as belonging to the Pleurocorallium norfolkicum species complex. The material matched colony fragments that have been traced to Vietnam.

Implications for the Trade

The discovery has some practical implications for the precious coral trade, particularly concerning regulation. The described angel’s skin coral necklace analyzed had initially been considered as being CITES listed because it was presumed to be Pleurocorallium elatius.

However, since the material was identified as the Pleurocorallium norfolkicum species complex, and a species never before considered by CITES, the CITES listing is no longer relevant for that specific material. What began as a forensic challenge in species identification has now become a valuable doorway to discovering new species within the precious coral trade.

In the 13th century, Marco Polo famously spoke of coral in Tibet saying “coral is in great demand in this country and fetches a high price, for they delight to hang it round the necks of their women and of their idols.”

As demand for high-quality precious coral material continues to increase, the regulation of the trade (e.g., through CITES) will remain important, as will ongoing efforts for marine conservation in producing regions such as the Mediterranean, Japan, Taiwan, and China. Education for consumers, alongside continued research into coral species, colors, treatments, and sources, is equally vital.

The cultural and historic importance of precious corals through the ages is evident, and through these continuous scientific advancements, the ability to trace and document these magnificent treasures of Nature provides greater transparency for the coral trade and ensures their important place in the world of jewelry.

Acknowledgements

We highly recommend Basilio Liverino’s book Red Coral─Jewel of the Sea to readers interested in learning more about the diverse history and world of precious corals. And we are grateful to Enzo Liverino and other members of the CIBJO Coral Commission for sharing their expertise with us.

References

• CIBJO, 2024. Coral Blue Book, 39 pp. https://cibjo.org/wp-content/uploads/2024/11/November-2024-Coral-Blue-Book.pdf
• Galopim de Carvalho, R., 2018., Precious corals, InColor, Vol. 38, pp. 70-78
  Lendvay, B., Cartier, L.E., Gysi, M., Meyer, J.B., Krzemnicki, M.S., Kratzer, A. and Morf, N.V., 2020. DNA fingerprinting: an effective tool for taxonomic identification of precious corals in jewelry. Scientific Reports, 10(1), p.8287.
• Lendvay, B., Cartier, L.E., Costantini, F., Iwasaki, N., Everett, M.V., Krzemnicki, M.S., Kratzer, A. and Morf, N.V., 2022. Coral-ID: A forensically validated genetic test to identify precious coral material and its application to objects seized from illegal traffic. Forensic Science International: Genetics, 58, p.102663.
• Lendvay, B., Morf, N.V., Cartier, L.E., Krzemnicki, M.S. and Nonaka, M., 2025. Trace DNA from a century-old holotype specimen resolves taxonomic uncertainties: the case of the Hawaiian pink precious coral (Pleurocorallium secundum), a CITES-listed species used in jewelry. Coral Reefs, 44, pp. 1211–1225.
• Lendvay, B., Cartier, L.E., Sato, A., Krzemnicki, M.S., Nonaka, M., Yasuda, N., Takata, K., Hayashibara, T., Morf, N.V., Iwasaki, N., 2025. Genetic testing of a high-end ‘Angel skin’ precious coral necklace identifies a species new to the precious coral trade and potentially new to science. Diversity, 17(6), p.395.
• Lendvay, B., Cartier, L.E., Sato, A., Krzemnicki, M.S., Morf, N.V., 2025. Species identification of coral jewellery by genetic testing: case studies, experiences and prospects. Journal of Gemmology, 39(7), pp.688-696.
• Liverino, B., 1989. Red Coral─Jewel of the Sea. Bologna, Italy. ◊

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