Mong Hsu is one of the reputed ruby deposits in Myanmar (Burma). It is located about 250km southeast of Mogok, in the Shan State, in northeastern Myanmar.
Zircon ZrSiO₄ a very intriguing mineral, not only because it can be used as an attractive gemstone (Figure 1) but also due to the fact that it can contain minute traces of radioactive elements (U, Th), which decay over time to lead (Pb) isotopes.
Copper-bearing tourmaline from Nigeria is known in the trade since about two decades (Milisenda 2001, Henricus, 2001; Smith et al., 2001; Zang et al., 2001). The first reported material from Nigeria was rather of aquamarine- to amethyst-like colours, but shortly after it was followed by a limited and sporadic p
by Dr. M.S. Krzemnicki, first published in Facette 27 (June 2021) Tourmaline is a mineral group of complex boro-silicates and is well known to produce gemstones in a wide range of beautiful colours. A specifically attractive variety is vivid yellow elbaite tourmaline, which owes its colour to manganes
by Dr. M.S. Krzemnicki, first published in Facette 26 (May 2020) In the past decade, rubies from Montepuez in the Cabo Delgado province of northeast Mozambique have been the most significant source of gem-quality rubies in the market. These include iconic stones such as the Rhino ruby (22.04 ct), the Scarl
In early 2019, an Australian client submitted a small series of gem- quality light green emeralds ranging from 2.01 – 5.80 ct in weight, which reportedly originated from the same rough crystal from the Riverina deposit in Western Australia (Figure 1). Known since the late 1970s (Whitfield, 1975), this deposit
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
A New Type of Emerald from Afghanistan’s Panjshir Valley. Published in Journal of Gemmology, 2021, 37 (5), 474-495.
Mogok-type rubies are known to contain small but distinct amounts of vanadium (often in the range of 0.015 – 0.025 wt% V2O3), but are commonly highly dominated by chromium (approximately by a factor of 20-100 x) responsible for their often attractive and saturated red colour and strong fluorescence. In some c