Zircon ZrSiO₄ a very intriguing mineral, not only because it can be used as an attractive gemstone (Figure 1) but also due to the fact that it can contain minute traces of radioactive elements (U, Th), which decay over time to lead (Pb) isotopes.
Zircon inclusions in unheated pink sapphires from Ilakaka, Madagascar: A Raman spectroscopic study. Published in IGC 2021 Online Proceedings, 21-23. https://www.igc-gemmology.org/igc-2021-online
by Dr. M.S. Krzemnicki, first published in Facette 26 (May 2020) The talisman of Charlemagne, a gem-bearing reliquary of historic provenance and importance closely associated to the history of Europe (Figure 1), was recently investigated by historians and gemmologists including from SSEF in a collaborative res
Presentation at the online 2021 International Gemmological Conference by Dr. Michael S. Krzemnicki.
by Dr. M.S. Krzemnicki, first published in Facette 26 (May 2020) In 2019, the Swiss Gemmological Institute SSEF in collaboration with the Istituto Gemmologico Nazionale IGN Rome (Italy) were able to analyse in detail a unique Roman sapphire intaglio (Figure 1), excavated in 1986 in the House of Gemmarius (
Raman spectroscopic investigation of zircon in gem-quality sapphire: Application in origin determination
Raman spectroscopic investigation of zircon in gem-quality sapphire: Application in origin determination. Published in Journal of Raman Spectroscopy, 2021, 1–11. Link to article
Having personally tested gemstones for more than 20 years now, the author of this short note was quite shocked in recent months to see distinct laser damage features on quite a number of sapphires which were submitted to us by different clients.
In 2016 the first emeralds appeared in the gem trade which reportedly came from new deposits discovered near the town of Shakiso in southern Ethiopia. Soon after, some of these stones partly of high quality were submitted to the SSEF and we were able to collect microscopic and analytical data and to integrate a
Fancy sapphires found in recent years in Madagascar brought to light colour stability issues. Some of these samples show an unstable colour, shifting from pinkish orange (padparadscha-like) to pink after a fading test are reported. We report on research findings on these stones and explain the causes and implic