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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...

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. ...

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...

by SSEF, first published in Facette 20 (January 2013)The studied non-nacreous natural pearl.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...

first published in Facette 22 (February 2016)Figure 1: Sapphire from Andranondambo (Madagascar). Photo: SSEFIn 2016, the SSEF received a sapphire of exceptional quality and size for testing (Figure 1). The sapphire of 33 ct was characterised by a saturated blue colour, - poetically also known...

by Dr. Michael S. Krzemnicki, first published in Facette 22 (February 2016)Figure 1: Rubies from Mozambique, from left to right: untreated, heated, heated, and fissure filled with lead glass. Photo: M. S. Krzemnicki, SSEFHeating of rubies from Mozambique at rather low temperatures is nothing...

by Dr. Michael S. Krzemnicki, first published in Facette 22 (February 2016)Figure 1: 6.02ct ruby in ring. Photo: V. Lanzafame, SSEFSimilar to fashion trends, gemmological issues challenging gem-testing laboratories have changed over time. In the 1980s, synthetic coloured stones threatened the trade....

first published in Facette 22 (February 2016)Figure 1: Exceptional spinel of 104 ct from Mahenge (Tanzania) together with a few small faceted spinels and spinel crystals from the same locality. Photo: M. S. Krzemnicki, SSEFIn 2007, the discovery of a huge pinkish-red spinel crystal...

first published in Facette 22 (February 2016)Figure 1: Samples A-C are from Kenya, sample D-E from Canada. Photo: M. S. Krzemnicki, SSEFDiopside, a calcium magnesium clinopyroxene (MgCaSi2O6), an end-member of the diopside-hedenbergite series (pyroxene) is a rather rare gem species in the trade. Commonly...