Since the end of the 20^th century, Ethiopia has established itself as a major player in the global opal market. The Shewa (or Shoa) and Welo (or Wollo) provinces, located on the Ethiopian plateau, are the two major producing regions of this precious gem. While Australian opals have long dominated the trade, Ethiopian opals are now attractive due to their variety, aesthetics, and the unique geological characteristics of their deposits. Their late appearance on the global market, combined with their distinct gemological characteristics, makes these opals a subject of both scientific and commercial interest.

Photo : Opal from Welo, Ethiopia © Rémi Bornet

The first documented discovery of gem opal in Ethiopia dates back to 1994, in Shewa Province, near Mezezo, on the northern flank of the Yita Ridge. These opals, sourced from welded rhyolitic tuffs, immediately attracted attention for their unique appearance, particularly their play of color visible in transmission (contra luz effect). Their appearance on the African market was initially discreet, before generating growing interest, amplified by the rarity of volcanic opal in major gem markets.

In 2008, an even more promising deposit was discovered in Welo Province, near Wegel Tena. This second source quickly revolutionized the image of Ethiopian opal due to the quality, variety, and superior stability of the material. Since then, Welo opals have dominated the international market in terms of volume and quality, directly competing with Australian opals.

Photo : Map of Ethiopian opal deposits © Rémi Bornet

The Shewa deposit is located approximately 240 km northeast of Addis Ababa, in a mountainous region that is difficult to access. The Yita Ridge site is perched at an altitude of 2,450 m and is only accessible by mule track or helicopter. The area is primarily rural, dotted with small farms. The site's isolation has long limited the development of opal mining, although some small-scale mining initiatives have been underway since the late 1990s. Opals are extracted by hand, without explosives, due to the material's fragility.

Welo, further north, offers easier access and geology more favorable to open-pit mining. The climate is semi-arid, which limits water alteration and promotes the opals' natural stability. The development of a real mineral sector, with sorting, cutting, and export from the region, is more advanced there than in Shewa.

Shewa opals form in a layer of welded rhyolitic tuff, similar to obsidian, dated to the Miocene (8 to 27 million years ago). This 3-meter-thick layer is inserted between layers of altered rhyolite, which are themselves located between basaltic layers. The opaline nodules, averaging 10 cm, are extracted from the cliff face. Typical inclusions (red or black grains, hollow tubes filled with secondary materials) reveal a complex formation environment, potentially related to late hydrothermal circulation. In places, manganese oxides such as ramsdellite accompany the nodules.

Geological section : Opal horizon sandwiched between volcanic layers, modified from Ayalew et al. (2003)

Welo opals develop in volcanic tuffs and more porous pyroclastic rocks. Their appearance is lighter, often milky, and they rarely present inclusions visible to the naked eye. The chemical alteration of volcanic matrices in a semi-arid context seems to have favored the precipitation of amorphous silica in cracks and voids, generating continuous opaline layers. Their deposit is more regularly exploitable, with a higher gem opal content.

In 1996, Shewa's production remained marginal (a few hundred kg), with a proportion of 15% of gem-quality opals, including only 1% with a clear play of color. The industry remains artisanal and highly sensitive to climatic and economic hazards. In the absence of infrastructure, local development is limited, and much of the material was exported unprocessed.

Welo province, on the other hand, has become one of the world's leading sources of opal in less than two decades. Extracted volumes are much larger, with a more favorable quality distribution. Welo opals, often cut into cabochons or faceted, are present at all major international trade fairs and regularly used in fine jewelry. Their relative abundance has created a veritable intermediate market, supplying production lines in India, Thailand, and the United States.

One of the major challenges of opal is the material's stability. Shewa opals, which are extremely porous, exhibit strong hydrophany : they absorb water, become translucent, then dehydrate and crack if conditions change suddenly. Laboratory tests have shown that cracks can appear after a few hours of exposure to heat or intense light. Their long-term durability in jewelry therefore remains questionable without prior stabilization.

Welo opals, although also hydrophanous, are more tolerant of humidity variations. Nevertheless, precautions should be taken : avoid thermal shock, prolonged wear in humid environments, or prolonged storage in dry atmospheres. Several workshops conduct stability tests before marketing (exposure under lamps, immersion and drying cycles). This helps distinguish stable opals intended for jewelry from those reserved for collection or decoration.

Some traders resort to treatments (oiling, resins, dyes) to strengthen or improve the appearance of the most fragile opals. Complete transparency regarding these processes is essential for market confidence.

Opal mining in Ethiopia is predominantly artisanal and informal, particularly in the Shewa and Welo provinces. Most mines are dug manually using rudimentary tools, without technical supervision or strict safety standards. Miners, often from local communities, work in precarious conditions, with little access to protective equipment or basic infrastructure. In some areas, children and adolescents are also involved in mining, raising significant ethical questions. The value chain is also largely dominated by foreign intermediaries who purchase rough stones at low prices, depriving mining communities of fair value.

To combat this value drain and stimulate local development, the Ethiopian government has implemented strict legislation on the export of rough opal since the 2010's. It is now prohibited to export uncut opals above a certain weight or without minimal processing in the country. This measure aims to encourage the cutting and polishing of opals on Ethiopian soil in order to create added value locally, promote the training of lapidaries, and establish a truly national gemological industry. Stones intended for export must therefore be accompanied by certificates issued by the Ministry of Mines and subject to stricter customs controls.

Despite these efforts, clandestine channels persist, fueled by strong international demand and a lack of on-the-ground control measures. Some traders still attempt to illegally export rough opals, circumventing the rules through informal networks. For the industry to gain credibility and sustainability, it is essential to improve transparency, strengthen mining cooperatives, and promote full traceability of Ethiopian gems. Ethical certification initiatives, inspired by fair trade, could ultimately offer a competitive advantage to Ethiopian opals, while guaranteeing better working conditions for miners and more balanced economic development.

Shewa and Welo opals perfectly illustrate Ethiopia's geological wealth. Their beauty, variety, and fragility make them unique gems, requiring special attention from gemologists, jewelers, and collectors alike. The gradual recognition of their value, combined with more responsible mining, could make Ethiopian opal a flagship stone of the 21^st century. The challenges of stability, ethics, and local development remain to be addressed to sustainably integrate this resource into a development agenda.