Gemstones have never played any significant economic role in the long history and rich culture of Ethiopia. It is only in the last two decades that Ethiopia has emerged in the gem trade. Rondeau et al. reported the discovery of large gemstone deposits in the country only recently.
The first high-quality emeralds from southern Ethiopia and sapphire from the north reached the market in the past few years. With all of these new materials reaching the market, the Gemological Institute of America (GIA) collaborated with the Ethiopian government to set up an expedition to the sapphire, opal, and emerald sources. Here, we focus only on sapphire.
Rumors of the sapphire discovery reached the Asian markets where the first stones were displayed. Since the initial discovery, sapphires have been found in many localities throughout northern Ethiopia.
The sapphires are mined and traded in the vicinity of Aksum. Since the mining area is remote and road access is limited, most of the transportation is carried out using camels and donkeys.
Despite the harsh and arid climate, people depend heavily on these animals for taking agricultural products to the market. Rainfall is scarce but intensely concentrated, which creates violent periodic rivers.
These high-energy water flows move boulders, rocks, and soil with enough power to wash away an entire fertile soil layer below which is found sapphire.
Ethiopian sapphire is sold in the local markets and dealers have set up offices in Aksum, where they buy gems. According to the study team, the trade there is limited to sapphire.
It is "illegal" for foreigners to go to the mining areas, let alone buy gemstones near the mines. However, local dealers take the item to Addis Ababa, where foreign buyers can purchase and export the gemstone.
Most of the foreign buyers improve the stones' appearance with heat treatment. Gem dealers gather in their offices during the weekly sapphire market. The study team reported that the local market has benefited greatly from the gem trade.
The flat land is covered with thick lava flows. These flows brought the "sapphires" to the surface and liberated them slowly while they eroded the soil.
The experts "observed" that the lava flows are still visible in the current topography, where all the plateaus are very flat and of uniform height.
These plateaus are crosscut by multiple broad valleys, which started as "V" shapes "eroding" in the basalts. Once they reached the harder basement, they started to widen to the broad valleys.
During weathering of the basalt, the main minerals broke down very rapidly. This means that more-resistant minerals accumulated in the debris. These heavy minerals were then transported by water to the center of the valley and became concentrated in deposits such as river bends or cavities.
Most of the mines are situated in the center of the valley, near the exposed riverbeds. This is where the highest "concentrations" of minerals are found. Some miners work higher up on the hillside, and "sapphires" have reportedly been found on top of the basalt plateaus.
This would indicate that the entire basalt plateau is sapphire bearing. In most places, the hills are terraced in an effort to limit soil erosion from heavy rainfall. To protect their food sources, "landowners" do "not" allow mining on land set aside for crops. The terraces on the hills are built to optimize agricultural yield.
In the mining area all activity is carried out with handmade tools. Crews of five to twelve people, including entire families, operate together. The GIA team observed the use of simple tools such as shovels and picks, with which the miners dig pits until they reach a gravel layer.
This layer is typically deposited straight on the hard rock basement. Gem-bearing gravel is "loosened" and thrown to the surface or passed along in buckets.
Miners dump the gravel onto the ground next to the pit, where it is searched by "hand" for sapphires. Wim Vertriest witnessed a family crew working together to extract sapphires from a pit.
This is often a completely dry process, with no washing or concentration involved due to the lack of water. Only in a rare case is the "water table" cut and the pit flooded. Some miners used a diesel pump to remove the excess water, while others removed it manually with buckets. The water is not used for washing purposes.
It is poured over the gravel to clear some of the finer sand. Overall the mining techniques are very primitive, and it is believed that this leads to a much lower yield. Only large stones with colors are picked out. Smaller stones covered in dust or mud, and other potentially valuable items are all discarded.
Yet it would be difficult to improve the situation under the circumstances. The "remoteness" of the area makes it challenging to bring in heavier equipment. Besides, the supply of fuel is erratic and irregular.
Water is scarce for communal services as the rivers are only seasonal. Seasonal floods make it hard to capture the water in a reservoir. This renders the current mining activity a strenuous one. As a result, local laborers earn wage through hard work in sapphire mining.
The sale of sapphire in the "local" market reduces the high price which could have been acquired at the international market. There is no device for transferring the true value of the gem to the miners.
As the local miners operate using traditional techniques of mining, both the quality and quantity of gems is low, reducing its market prices. Shortage of modern tools of mining, lack of skills in using these tools, inadequate infrastructure, and absence of competitive gem market all hamper the production and exchange of sapphire.
The gemstones found in northern Ethiopia are mainly blue sapphires. According to the GIA experts, they show characteristics very similar to sapphires from "other" deposits, such as those in Australia, Thailand, or Nigeria.
These deposits are called BGY sapphire deposits because they predominantly yield blue, green, and yellow (BGY) colors. They also routinely produce "black" sapphires, which are expensive at the international market.
The majority of Ethiopian sapphires are blue, with a few pure yellows. The locals describe these as "zebra sapphires." Fully black sapphires and star sapphires have "not" been observed by the study team.
High-quality blue sapphires are discovered in northern Ethiopia. The color of these sapphires ranges from dark greenish blue to a pleasing light blue. A yellowish cast is often observed with a torch.
Technically speaking, this is due to the scattering of light when it interacts with the small particles. Ethiopian sapphires are characterized by a variety of inclusions similar to those observed in sapphires from other sources.