The Challenge: Identification of a Ramaura Synthetic Ruby
by Dr. Michael S. Krzemnicki, first published in Facette 22 (February 2016) Similar to fashion trends, gemmological issues challenging gem-testing laboratories have changed over time. In the 1980s, synthetic coloured stones threatened the trade. But since the early 1990s, the challenge has switched to trea
Spinel from Mahenge (Tanzania) and its Heat Treatment
first published in Facette 22 (February 2016) In 2007, the discovery of a huge pinkish-red spinel crystal of 52 kg in the carstic marbles at Ipangko south of Mahenge (Tanzania) resulted in a sudden supply of spinels (up to 100 cts) of a vibrant pinkish-red colour, which immediately mesmerized the market.Ap
Undisclosed natural diamonds mixed in a parcel of synthetic diamond
by J.-P. Chalain, first published in Facette 22 (February 2016) In 2016, our Diamond Department acquired a parcel of small colourless synthetic diamonds produced in Europe by the HPHT method. The complete study of these series of melee size synthetic diamonds (SSEF Research project 80602) is part of our co
Colourless Diopside from Kenya and Canada
first published in Facette 22 (February 2016) Diopside, a calcium magnesium clinopyroxene (MgCaSi2O6), an end-member of the diopside-hedenbergite series (pyroxene) is a rather rare gem species in the trade. Commonly found in greenish brown stones (mostly due to iron content) to dark brown cabochons with an obl
Zircon Showing Asterism
first published in Facette 22 (February 2016) Martin Steinbach, a collector of star stones from Idar-Oberstein (Germany), submitted to the SSEF a zircon with a star effect (asterism), which – to the knowledge of the author – so far had not been described in literature for this gem. The zircon speci
Paraiba Tourmaline Intergrown with Lepidolite Mica
by Dr. M.S. Krzemnicki, first published in Facette 20 (January 2013) The Swiss Gemmological Institute SSEF recently received a necklace for testing that consisted of thirty-three slightly polished light blue to greenish-blue and purple beads. It had originally been sold as Paraiba tourmaline to our client. The
Colour-Changing Zircon
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
CVD Synthetic Diamonds and Testing at SSEF
by J.-P. Chalain, first published in Facette 20 (January 2013) Synthetic diamonds have been present in the gem trade for over two decades. Recent financial investments and advances in technology have now made them more affordable both in terms of price and availability. The SSEF has been following synthetic di
X-Ray Computed Microtomography at SSEF
by Dr. F. Herzog & M.S. Krzemnicki, first published in Facette 20 (January 2013) For the last few years SSEF has seen increased demand for analysis of pearls. This is not astonishing. On the one hand, the supply of natural pearls that grow or were grown without any human intervention is limited. On the oth
Jade, Stone of “Gods”: Terms, Concepts & Certification
Jade, for thousands of years a mythical stone appreciated in the Far East and in the high cultures of Native Americans, is rising high at present as it is sought after at auctions in Hong Kong and elsewhere. However, the term “jade” is quite vaguely defined. Different concepts try to describe the term based