Rumours about the discovery of new sapphire deposits in northern Ethiopia have been circulating in the industry since February 2017. This rumour gained traction when one of the authors (SB-L) visited mining areas in the Tigray region in June. The city of Aksum became a hub for gem traders, while mining activities were mainly concentrated around the town of Chila, about 25 kilometres northwest of the city.
According to literature reports, Ethiopia's sapphire producing areas consist of secondary mineral deposits and the gemstones produced are round crystals. Most rough stones weigh around 2-3 grams, but there are reports of crystals weighing over 50 grams, but larger crystals tend to crack. Heat treatment trials are currently underway in Chanthaburi, Thailand and Beruwala, Sri Lanka to assess the quality of the material. It is estimated that 5-10% of sapphires do not require heat treatment.
At the end of April this year, the first batch of sapphire samples arrived in Bangkok for analysis by GIA researchers. The samples range in colour from dark to light blue and many contain tiny grains of rutile, some even showing a Dabitz-like pattern. In addition, some stones also appear green or yellow, and in bicolour sapphires a combination with blue occurs. GIA research shows that all of these sapphires exhibit strong blue-green pleochroism.
To further understand the chemical composition of these gems, the researchers performed elemental analysis on both samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The results showed clear differences in the chemical composition of clean and particle-rich areas, demonstrating the complexity and diversity of the gemstone.
Since May, many Sri Lankan gem dealers have travelled to Ethiopia to purchase the newly discovered sapphire material, causing a sharp rise in prices in the local gem market. Although all mining activities are artisanal, impressive results have been achieved in a short period of time. However, the timing and results of heat treatment of these deposits will determine their commercial viability.
This discovery has caused great excitement among industry insiders and has also brought new hope to the Ethiopian gemstone industry. With further research and development underway, this newly discovered sapphire deposit is expected to breathe new life into the global gemstone market.
