Blog & News

Travelog / school

The vocational training center of Arusha, Tanzania

Lauriane Pinsault; March 2023

Students at the VTC (Vocational Training Center) in Arusha

Our second stop in Tanzania brings us to Arusha, an important place in the country for colored gemstones trading, thanks to the famous TanzaniteOne mine (the only known tanzanite mine in the world), located nearby in Merelani Hills


We were welcomes at the Vocational Training Center (VTC) of Arusha, a gemmology and faceting school, to visit their facilities and discuss about the gemstone industry within the country. 

The VTC exists since 2000 and has trained more than 800 students since its opening, which represents, according to the director of the school, more than 97% of the certified cutters in the country. The cursus includes gemstones identification, grading and sorting, but mainly focused on cutting lessons, over a 6-month program. The students are trained on both local and international cuts. Both types of cuts are done following indexes for angles between facets, but crudely, the difference relies on the retention of the weight. Locally, the cutters tend to retain more weight because they feel they get a better price (as gemstones are bought in $/ct). However, these local cuts are very often recut to integrate the international market, who demand higher quality of cut over weight (perfect symmetry, optimized proportion for light refraction and dispersion, etc). The students start their cutting training on marbles, before moving to natural gemstones.


Facetting work in progress on marbles

Fixing the gemstone with dop

Facetting machine

Student working on the preparation of the gemstone table, before facetting

Lauriane discussing with a student about fecetting methods

The number of students per section varies a lot, mainly depending on the economical and political situation. Since the change in politic regime in 2015, the school observed a significant decrease in students’ registrations. They also fundamentally rely on the industry, for example the closure of TanzaniteOne mine was a major hit it was the main hiring company for many certified students. The current situation is difficult for the school, particularly with the impact of Covid and the Ukranian conflict, due to the lack of work opportunities after graduation. The director stressed that the school is still opened nowadays thanks to the support of the NGO GemLegacy who played an important role in the existence of the center for several years now. 

Conversation around the gemstone sector highlighted the opportunities and challenges in the country. The discovery and development of tanzanite mining in Merelani led to a strong social and economic growth of the region, but also of the entire Tanzanian gemstone industry. According to the director of the VTC, the major current brakes the sector are mostly related to the lack of governance and poor regulations. The country and people would benefit more of the true value of their gemstones if they were cut within the country, in line with the law on tanzanite that officially request all tanzanite’s above 2g to be cut before the export. In reality this regulation is loosely enforced and tends to encourage smuggling more than in-country beneficiation. The director argues that they do have trained labor force in the country to ensure the beneficiation process as many students have been graduated from his school in the past 23 years, and they could absorb more if the need was there. Another example of regulations that could promote the local skills, gemstones and sector would be to enforce the gem master dealers in the country to have cutting machines*.


The school director, Lauriane and the school teacher

We are very thankful to GemLegacy for
putting us in contact with the VTC, and a big thanks to the VTC staff and
students for sharing their knowledge and experience. 

*The articles on this blog relate the opinion of industry actors, and therefore should not be considered as GeoGems point of view, which remains neutral. It is for every reader to learn, think, reflect, and debate on the raised subjects.
Travelog / Mining

Artisanal Mining in Morogoro, Tanzania

Lauriane Pinsault; January 2023

Visit of a mining site, with the chairman of the Matombo miner association, a women artisanal miner, and Alpha from PDI tanzania

In January 2023, GeoGems had the chance to visit an artisanal ruby mining site in Tanzania.

A massive thanks to Alpha Ntayomba, executive director of Population and Development Initiative (PDI) in Tanzania, who organised this visit and welcomed us in Morogoro. PDI is an NGO, originally based in Kigoma (west of Tanzania, on the edge of Tanganyika lake), now installing an office in Morogoro. Morogoro, and the whole Uluguru mountains, are well renowned for gemstones, including corundum, spinels, amethyst and garnets. In this gem-rich area, PDI promotes responsible mining amongst ASM (Artisanal and Small scale Mining) communities, on various commodities from gold to gemstones.

We were also accompanied to the mining site by the chairman of the Matombo Miner Association, himself a miner in the area for the past 30 years.

Exploitations are all open-pits, 5 to 10 m deep, making the extraction pretty easy for artisanal exploitation. However, no safety equipment is in use (the miners are even operating bare foots), and many old pits were left abandoned. The miners told us that the size of the ruby deposit was about 1km², with around 100 artisanal miners working on the different concessions. Considering the wide gem-rich area, the number of miners operating around is much likely higher.

As the deposit is on privately owned land, the miners pay an exploitation fee to the landowner and operate legally with a licence to mine. Miners are generally organised in groups of 3 to 10 people, with dedicated roles and a leadership system. However, no formal contracts exist between them: they share the revenues from the sales based on verbal agreement. Very few women are involved, and when they are, they mostly take care of the food and logistics. Sometimes, the landowner is also a miner himself, in which case he gets the “rent” for the land, plus the share of revenue from the sales. The miners admitted that this informal organisation on the division of the revenues could sometimes lead to conflicts. 


Artisanal miners working in Matombo

Pits and bags of ores at the artisanal mining site

The mine visited was located in Matombo, and produces mostly red corundum (rubies), pink spinel and green tourmaline. The deposit is secondary, with the gemstones found in a layer of red soil. Big crystals of quartz and schorl were also part of the ore. The miners explained that they were following a layer composed of big pebbles of quartz and aggregates of minerals, which they consider being an indicator for the presence of rubies and spinels. No gemstones were directly found on site (from the pits or the ore) during our visit, but quickly the miners showed us some of their production. Notably, their best “rubies” was a bring fluorescent pink spinel (with a nice and clear octahedron shape). Indeed, miners are doing the distinction between rubies and spinels based on the colour only, which leads to errors in identification.

The production is variable, especially with the season as the mining activities are more important during the dry season than the rainy season. This is because most of the miners have another occupation, often farming. From the mine visited, about 10kg of gemstones was produced per month (unclear if it is comprising all gemstones or only corundum). The rubies that were showed to us were all of medium to low quality, showing good colour but bad clarity. 

Once produced, the gemstones are roughly graded into different quality categories before sales. For the past 2 to 3 years, the Tanzanian government has opened markets and auction places, in order to encourage miners and buyers to declare their production and sales, and thus to pay the related taxes. In Matombo, the “auctions” take place twice a week, and bring together hundreds of miners for about ten big buyers. Buyers are often from other countries like Kenya. Although they see this selling place as a good opportunity for them, the miners admitted that what they are looking for is quick profits, so they continue to sell directly to buyers if they are approached outside of the auction time and place. The revenues from the mine visited are between 800 000 TSH (344 USD) and 3 000 000 TSH (1 290 USD) per month. Considering 10kg of gemstones produced per month, that an average sale around 0,02 ct/$. Also considering that 6 miners were operating at this site, is gives an average wage of 500 000 TSH (215 USD), corresponding to the minimum wage for mining companies in Tanzania[1].


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Production from the Matombo mining area, comprising of spinels, rubies and green tourmaline

Pit and nature surrounding in Matombo

This visit represented well the complexity of the ASM sector, and notably for the extraction of gemstones. First, the miners are operating legally, and make a living out of the sales of their production. They organise as they consider is the best and have been operating this way for many years. However, the lack of formal arrangement on the share of revenue, as well as safety standards, which could lead to human rights abuses and major injuries. The will for quick profits, combine with the mistake in gemstone identification and quality, is also a threat because it leaves space for the buyers to purchase the production at lower value than it is worth, especially when buying outside of the government marketplaces. Addressing the challenges of the sector to efficiently implement responsible mining in such context entails for all actors (miners, buyers, governments), to agree on a common strategy and global vision, and for each to find a benefit in it, which is yet to be done.

Note on history:

Morogoro region is vast, and many gemstone deposits are found there, with, amongst the most famous ones, Kitonga, Lukande, Matombo and Mahenge. Rubies from Morogoro are known since the 1970s, but the gemstone arrived in the market in the 1980s[1], peak of production happen between the mid-1980 and the mid-1990s[2]. The production in 1992 was estimated to be around 200kg per month, with quality being again mostly cabochon and carving grade[3].

[1] Hänni, H. A., & Schmetzer, K. (1991). New rubies from the Morogoro area, Tanzania. Gems & Gemology, 27(3), 156-167.

[2] Hughes, R. (2008) Gem Hunting in Mahenge & Tunduru.

[3] Schwarz, D., Pardieu, V., Saul, J. M., Schmetzer, K., Laurs, B. M., Giuliani, G., … & Ohnenstetter, D. (2008). Rubies and sapphires from Winza, central Tanzania. Gems & Gemology, 44(4).


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