first published in Facette 22 (February 2016)Figure 1: Water-worn pebble and cut stone, both polycristalline kyanite.The Swiss Gemmological Institute SSEF received two blue translucent samples, a water-worn pebble, and a faceted stone of 1.72 ct cut from the same piece (Figure 1). ...
first published in Facette 22 (February 2016)Chrysoberyl is found in various colours, mostly yellow to green and brown due to iron, light green to bluish green (vanadium) or as the colour-changing variety alexandrite (due to chromium).In rare cases, chrysoberyl is also found in...
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...
Figure 1: Part of the studied danburites for this research project. Photo: M. S. Krzemnicki, SSEFThe calcium-boron-silicate danburite is a rather rare collector’s stone, mainly known in colourless to slightly yellowish to brownish colours from a limited number of deposits worldwide. Since 2013, new and...
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...
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...
by SSEF, first published in Facette 20 (January 2013)Although pearls, as organic gems, are commonly less stable than polished gemstones, we don’t often see pearls with obvious features of surface damage as a result of unfortunate care.A few months ago, however, we received for...