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
ကျောက်မျက်များ၏ရောင်ကွဲများ နှင့် ၎င်းတို့ကိုဘယ်လိုခွဲခြားသတ်မှတ်မလဲ။
ကျောက်မျက်ရတနာဆိုသည်မှာ သဘာဝအတိုင်းဖြစ်ပေါ်လာတဲ့ တွင်းထွက်တစ်ခုပင် ဖြစ်သည်။ တွင်းထွက်များ၏ အမည်နာမများကို နိ
The Usambara Effect and other colour-change Effects in Gemstones
Colour change in gemstones is an interesting phenomenon, which can be due to a number of reasons. One of the causes is the so called Usambara effect, a type of colour change which is not so well known in the public. In contrast to the alexandrite effect, this phenomenon is not dependent on the type of illuminat
Fake Historic Provenance: ‘Aged ’ Cultured Pearls
Most recently, we received a pearl necklace with 410 pearls strung on three regularly graduated strands. The pearls were characterized by a beautifully matching colour and a fine pearl lustre, reminiscent of ‘classic’ natural pearls from the Arabian Gulf. However, a closer look using X-ray luminescence (SSE
Historic Sapphire of Catherine the Great
SSEF had the pleasure to add to this eclectic (data) collection the famous sapphire of Catherine the Great, a historic gem from Ceylon (Sri Lanka) of exceptional quality and beauty.