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.
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.
Fissure-filling in Paraiba Tourmaline
As with any gemstone with fissures, it is of no surprise that some Brazilian Paraiba Tourmaline is filled with a colourless foreign substance (mostly artificial resin) to modify and enhance its transparency and thus apparent beauty.
Fake Tridacna Pearls
Fake pearls are beads (of whatever shape) which have been cut entirely from shell material. A perfect source for the production of such fake pearls is the Tridacna clam, amongst the largest living bivalve mollusc with a massive and thick shell of up to 110 cm diameter, mainly living along shallow coastal water
Neutron and X-Ray Tomography of Emeralds
Since two years, the SSEF has been working with the Laboratory for Neutron Scattering and Imaging at the Paul Scherrer Institute (PSI) using their ICON beamline (cold neutron imaging) at the SINQ spallation source. The aim of these research projects in collaboration with Dr. Lehmann and Dr. Mannes is to analyse
Rarities and Collector Stones Tested at SSEF
The daily routine at SSEF usually consists of testing rubies, sapphires, emeralds, pearls and diamonds. Although sometimes challenging and interesting, especially taking into account the quality and the documented historical provenance of some of these gems and jewellery items, it is also always of great intere