Heat treatment of ruby, sapphire and other colour varieties of corundum is one of the main issues for the gem trade. As such, detecting such treatment is a major task of gemmological laboratories issuing gemstone reports. Unfortunately, and especially lately, the detection of such heating is not always straight
Titanium diffusion treatment is known since decades: it can lead to a surface-related blue colour in corundum. Basically, this treatment is a heating process requiring high temperatures in combination with titanium (oxide) as an additive. During the treatment, titanium atoms penetrate into a superficial layer o
Padparadscha is one of the most attractive corundum varieties in the trade and is sought after for its subtle pinkish orange to orangey pink colour. Padparadscha, originally known from Sri Lanka only, is found today also in other deposits such as for example in Madagascar and Tanzania, both part of East Africa
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.