Jos is the capital of Plateau State in central Nigeria. It sits on the Jos Plateau at an elevation of around 1,200 metres and has been, since the colonial period, the most important inland trading and processing centre for Nigerian coloured stones. For the gem trade Jos is significant for three reasons: its long history as a tin and columbite mining centre, the cool climate that made it a secondary administrative hub, and its present-day role as a clearing-house for tourmaline, sapphire and aquamarine produced from the surrounding pegmatite belts.

Historic mining background

The Jos Plateau was the centre of British colonial tin mining from the early twentieth century. Tin and the associated mineral columbite, a major source of niobium, were the principal exports until the 1960s. The infrastructure built around tin mining, including processing yards, a railway connection to the coast and a sizeable expatriate technical community, gave Jos an unusually deep mining tradition for an inland Nigerian city. When the tin economy declined, much of that infrastructure was repurposed to handle the artisanal coloured stone production that emerged from the Plateau and the wider central belt.

Modern coloured-stone trade

Today Jos handles material from a wide arc of West and Central Nigerian deposits. Tourmaline, including elbaite and chrome tourmaline, comes from the wider Plateau and Nasarawa areas. Sapphire is brought in from Kaduna, Bauchi and Mambilla. Aquamarine, heliodor and morganite arrive from the pegmatites of Kaduna and Plateau States. Garnet, both pyrope-almandine and demantoid in small quantities, is also traded. Most of the rough is bought from artisanal miners, sorted in Jos, then sold either to local cutters or, more often, exported as rough to Bangkok and Jaipur for cutting and certification.

Trade structure

The Jos market operates through a network of dealer offices and informal trading rooms rather than a single bourse. Buyers from Thailand, India, Sri Lanka and increasingly China have maintained long-term relationships with Nigerian dealers there for several decades. The trade has been intermittently disrupted by the security situation on the Plateau since the mid-2000s, which has affected travel patterns more than the underlying flow of rough. Despite these difficulties Jos remains the dominant inland gem city in Nigeria, ahead of Ibadan, Kaduna and Kano for coloured-stone volumes.

Significance

For the international trade Jos is the single most efficient point of entry to Nigerian coloured stone production. Stones marketed simply as Nigerian tourmaline or Nigerian sapphire have, in the great majority of cases, passed through Jos on their way to the cutting centres. Understanding the city's role is therefore essential for anyone trying to verify origin claims for West African material.