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
first published in Facette 22 (February 2016) In 2007, the discovery of a huge pinkish-red spinel crystal of 52 kg in the carstic marbles at Ipangko south of Mahenge (Tanzania) resulted in a sudden supply of spinels (up to 100 cts) of a vibrant pinkish-red colour, which immediately mesmerized the market.Ap
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
Sapphires Heated with Pressure – A Research Update. Published in InColor, Spring 2019, 86-90.