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...
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...
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)...
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...
first published in Facette 22 (February 2016)Figure 1: 13 ct star zircon. Photo: V. Lanzafame, SSEFMartin 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...
by Dr. M.S. Krzemnicki, first published in Facette 20 (January 2013)Necklace with thirty-three polished beads, sold as Paraiba-tourmaline proved to be a complex intergrowth of Paraiba-tourmaline with lepidolite. About a third of the beads were identified as lepidolite only, showing purple colour and...
by Dr. M.S. Krzemnicki, first published in Facette 20 (January 2013)Two impressive zircons from Burma (56 and 13 ct) show a colour change from greyish blue to slightly purplish-blue in daylight to green and greyish green in incandescent light. Their colour change is the...
by Dr. M.S. Krzemnicki, first published in Facette 20 (January 2013)Nowadays, sapphires from Kashmir are among the most expensive and sought-after gems on the market. Just to highlight this, a Kashmir sapphire of 8.91 ct in a ring was sold in December 2012 at...
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...