Green spodumene sold as emerald imitation
Spodumene crystals (longest item about 50 cm long and 5.9 kg heavy) submitted to SSEF as new 'emeralds' from Pakistan shown here together with a faceted emerald from Pakistan
Age dating as a testing procedure for gemstones and biogenic gems
by Dr. M.S. Krzemnicki, first published in Facette 26 (May 2020) Radiometric age dating is a well-established method in geochronology (Earth sciences) and archaeology. There are numerous studies highlighting the use of radioactive decay of U-Pb, K-Ar (amongst many others) for geological age dating and radiocar
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
Chipping of Emeralds
The cleaning process of emeralds, often supported by mechanical tumbling and ultrasonic cleaning may result in chipping or even cracking of pre-existing fissures within emeralds at any time afterwards.
Beware: Laser Damage in Sapphires due to Jewellery Repair
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.
Study of opalised Dinosaur Vertebra
Recently, the Swiss Gemmological Institute SSEF received an exceptional opalised dinosaur vertebra for study. This specimen was reportedly from Lightning Ridge (New South Wales in Australia) – a world famous source of dark opals and opalised plant and animal fossils - and was already photographed by Elizabeth
by Dr. M.S. Krzemnicki, first published in Facette 20 (January 2013) After studying and describing colour-changing bastnäsite in the 2012 Facette (Herzog 2011 & Herzog 2012), we have this year focussed research on colour-changing zircon from Burma in collaboration with Mr. O. Waldis, who kindly lent us a
The Usambara Effect and other colour-change Effects in Gemstones
Colour change in gemstones is an interesting phenomenon, which can be due to a number of reasons. One of the causes is the so called Usambara effect, a type of colour change which is not so well known in the public. In contrast to the alexandrite effect, this phenomenon is not dependent on the type of illuminat
A Case Study of Ivory Species Identiﬁcation Using a Combination of Morphological, Gemmological and Genetic Methods
A Case Study of Ivory Species Identiﬁcation: Using a Combination of Morphological, Gemmological and Genetic Methods. Published in Journal of Gemmology, 2020, 37 (3), 282-297.
The Beryl Group – an Overview
The Beryl Group – an Overview. Published in Journal of the Gemmological Association of Hong Kong GAHK, 2020, Volume XLI, 48-54.