The spinels were nearly free of any inclusions except for a few tiny colourless forsterite inclusions. In combination with trace element analyses, the origin of these spinels could be unambiguously attributed to the famous spinel mines near Kuh-i-Lal, located in the Pamir mountains in southern Tajikistan, close
Imagine life as an emerald. Just born in the rocks and growing, you get joggled and bruised by mother nature and later by the mining process. So, already in your young age you carry quite some scars and fractures, which reduce your true beauty considerably and may not make it so easy to find a good mate (emeral
The body colour of pearls is normally related to the presence of natural colour pigments produced by the mollusc during pearl formation. Another option is to colour pearls artificially, with dyeing being the most readily available method. Often applied to rather low-quality freshwater cultured pearls, these tre
by Dr. M.S. Krzemnicki, first published in Facette 27 (June 2021) It cannot be repeated often enough: any gemstone which contains fissures is prone to be treated with fissure filling substances, either by using a colourless or coloured substances (e.g. oil). Even when the stone comes from a famed mini
Rubies from Mong Hsu, located about 250 km southeast of the Mogok Stone Tract, entered the gem trade in the early 1990s. Since this time the Mong Hsu mines remain an important source for Burmese rubies, specifically for stones of smaller sizes (2 ct and below).
Zircon inclusions in unheated pink sapphires from Ilakaka, Madagascar: A Raman spectroscopic study. Published in IGC 2021 Online Proceedings, 21-23. https://www.igc-gemmology.org/igc-2021-online
Presentation at the online 2021 International Gemmological Conference by Dr. Michael S. Krzemnicki.
Raman spectroscopic investigation of zircon in gem-quality sapphire: Application in origin determination
Raman spectroscopic investigation of zircon in gem-quality sapphire: Application in origin determination. Published in Journal of Raman Spectroscopy, 2021, 1–11. Link to article
by Dr. Michael S. Krzemnicki, first published in Facette 22 (February 2016) Heating of rubies from Mozambique at rather low temperatures is nothing new. Immediately after the discovery of this new deposit close to Montepuez in 2009, it was obvious that part of the new material required heat treatment befor
There is a long established tradition in the trade to fill open fissures in emeralds with colourless fillers, such as oil, wax and (artificial) resins, to reduce their visibility. Disclosure of such treatments is mandatory (CIBJO), including a quantification of the filler substance, as this may have a direct im