Colour-Changing Zircon
by Dr. M.S. Krzemnicki, first published in Facette 20 ( […]
CVD Synthetic Diamonds and Testing at SSEF
by J.-P. Chalain, first published in Facette 20 (Januar […]
X-Ray Computed Microtomography at SSEF
by Dr. F. Herzog & M.S. Krzemnicki, first published […]
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 တွင်းထ […]
เกณฑ์การเทียบสีและการกำหนดชื่อเฉพาะของอัญมณี
พลอย อัญมณี หรือรัตนชาติ ส่วนใหญ่เป็นแร่ ซึ่งเป็น […]
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.
The Detection of HPHT-treatment of Diamonds at SSEF: 20 Years later
In 2000, SSEF announced that it was able to identify the HPHT treatment of type II diamonds. About 20 years later, this article summarizes how we were able to achieve this breakthrough and which people from the trade and other research institutions were involved in this important step.