Emeralds and the Saga of Cleaning and Filling Fissures
There is a long established tradition in the trade to fill open fissures in emeralds with colourless fillers, such as oil, wax and (artificial) resins, to reduce their visibility. Disclosure of such treatments is mandatory (CIBJO), including a quantification of the filler substance, as this may have a direct im
Research on Golden Cultured Pearls
In February 2016 Dr. Laurent Cartier had the opportunity of visiting Jewelmer pearl farms near Palawan Island in the Philippines and observing the different culturing techniques required to harvest golden South Sea pearls.
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
Strange Mushroom Pearl
by SSEF, first published in Facette 20 (January 2013) In 2012, we again received a number of pearls with strange shapes for testing. The most extravagant and intriguing of these curiosities of nature was a non-nacreous brownish natural pearl from a marine mollusc, which closely resembled a mushroom (see ph
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