Assocoral, the Italian coral traders Association, in collaboration with IGI Istituto Gemmologico Italiano, presented on July 17th in Torre del Greco a new coral certification scheme in a meeting focused on the main gemological features of this coveted precious stone.
Dr. Loredana Prosperi, lab director of Istituto Gemmologico Italiano, informed on coral classification of the 8 precious coral species available in jewelry trade: Rubrum, Japonicum, Elatius, Konojoi, Secundum, Laauense, Sulcatum, Regale.
In her speech Dr. Prosperi provided an overview on the currently available chemical investigations apt to identify the main coral species. For instance higher Barium and Lead contents may reveal the possible provenance from Mediterranean Sea (Rubrum) while lower contents can indicate the origin from Pacific Ocean (Japonicum). FTIR and Raman spectroscopy can be useful to determine the presence of fillers such as wax or other artificial dying materials.
Dr. Anna di Cosmo, from Department of Zoology and Biology of Federico II University of Naples, made the point on the gemological aspects of corals and illustrated the new identification and classification technique based on DNA data.
This bioinformatic analysis requires an aseptic environment typically named “white room”, an ISO9011 certified laboratory allowing to correctly sequence the genome of the material (weighing in between 20 to 50 mg, 0.12-0.25 carats) extracted through the use of a drill, in absence of any alteration caused by external elements. The procedure will lead to revealing the taxonomic nature of the analyzed samples providing phylogenetic details of the species under investigation.
Delivery time and costs of this new analysis have been also considered during the meeting. Currently about 3 weeks are necessary to produce the new DNA-based certificate while costs were not specified. Anyway this analysis is supposed to be recommendable only for high-value pieces since DNA, in case of necklaces, must be ablated for any single bead. Dr. Di Cosmo pointed out that the procedure needs a small quantity of ablated material and therefore it is more suitable for drilled products rather than for loose stones.
DNA analysis has not been conceived only for gemological purposes but also for the determination of the geographical provenance since informations on the bathymetric origin are provided as well. This can result in the identification and traceability of corals coming from protected and restricted areas distinguishing precious corals from other endangered species.
