This content was first published on IGR – Italian Gemological Review no. 19 in 2024. The information provided here is therefore current as of the original publication date.
The Mediterranean Gem and Jewellery Conference took place in Cavalese, Italy, from May 7-9, and continued in Piran, Slovenia, from May 10-11, 2024, presenting an exceptionally advanced work program. As usual, the workshops on specific identification were structured around theoretical sessions complemented by practical exercises.
A particularly interesting aspect of these meetings on colored gems and diamonds, developed by Branko Deljanin, is that they go beyond theoretical discussions to include practical applications with various instruments. Given the advanced skill level of the participants, each edition allows for the review of highly relevant specific cases.
What’s the hottest issue all laboratories are working on when it comes to gemstone identification? The hot topic is undoubtedly the determination of provenance. Using specific samples, Lore Kiefert, with her great expertise, reviewed the geological formation and genesis of corundum, beryl, and major commercial gemstone deposits for the participants. Emerald deposits are categorized into Type I, related to tectonic magma with various subtypes (Brazil, Zambia, Russia, China, Canada, Norway, Kazakhstan, Australia, Nigeria), and Type II, related to tectonic metamorphism with subtypes found in Brazil and Austria; black sedimentary-schist rocks (Colombia, Canada, USA) and metamorphic rocks (China, Afghanistan, USA). Spectral differences between the Paraiba elbaites of the Brazilian state and those of Africa were also highlighted. Participants could assess their knowledge through a fun quiz organized by the charismatic Lore.
Branko Deljanin’s work on diamonds complemented this microscopic investigation of colored stones. He started with basic instrumentation analyses such as polariscope, microscope, and standard UV lamp, then moved on to observing fluorescence and phosphorescence from short waves using affordable and intuitive equipment like the Gemetrix (PL-Inspector). Once oriented, participants were guided to in-depth workshops using MAGILABS instrumentation (FTIR, Raman, EXA, Uv-Vis-NIR).
Spectrophotometry provided a detailed analytical insight into detecting not only synthetic diamonds but also specific cases such as the tricky HPHT-treated natural diamonds. The highlight of the conference was the spectral analysis, where Mikko Åström and Alberto Scarani, expert developers of the instrumentation, successfully addressed topics suggested by the participants’ curiosity and direct experience, such as the heating of spinels and the recognition of sapphires with reduced chromium.
Article by Francesco Sequino, published on IGR – Italian Gemological Review #19 – Autumn 2024.
