Spinel from Mahenge (Tanzania) and its Heat Treatment
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
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
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.
Rubies with Oil in Fissures
Over the past few years, the SSEF has repeatedly seen gemstones (apart from emeralds) which contained fissures filled with oil or other fillers. These include rubies, sapphires, spinels, tourmalines, garnets and even rarities such as pezzottaite.
Sapphires Heated with Pressure – A Research Update
Sapphires Heated with Pressure – A Research Update. Published in InColor, Spring 2019, 86-90.
Cobalt diffusion-treated spinel
Cobalt diffusion-treated spinel. Published in IGC Namibia 2017 Abstract Proceedings, 151-153. Author(s): M.S. Krzemnicki, H.A.O. Wang, T. Stephan, U. Henn
Emeralds and the saga of cleaning and filling fissures
Emeralds and the saga of cleaning and filling fissures. Facette (2017) Author(s): M.S. Krzemnicki
Ruby heat treatment and fracture repair
Ruby heat treatment and fracture repair. Published in Jewellery News Asia, 2001. Author(s): H.A. Haenni
Species identification and treatment detection in dark coloured pearls
Species identification and treatment detection in dark coloured pearls. Published in 2015 Swiss Geoscience Meeting Abstract Proceedings, 134-135. Author(s): W. Zhou, T. Dzikowski
Be-detection by FTIR on corundum; a preliminary report
Be-detection by FTIR on corundum; a preliminary report. Published in IGC 34 Lithuania Abstract Proceedings, 69-71. Author(s): W.A. Balmer, M.S. Krzemnicki