Kunar tourmaline is the trade designation for elbaite-series tourmaline mined from the granitic pegmatites of Kunar Province in eastern Afghanistan, part of the broader Nuristan pegmatite belt that extends across the Pakistan border. The name refers to a region rather than a discrete locality, and material from Kunar, Nuristan and adjacent Pakistani districts is often commingled in the international trade.

Variety range

Kunar pegmatites produce elbaite across nearly the full elbaite colour spectrum: pink to red rubellite, green elbaite (often grading from yellow-green to deep green), blue indicolite, and bicoloured stones including pink-and-green watermelon material. Achroite (colourless elbaite) and parti-colour combinations of three or four hues in a single crystal are also documented. Crystals tend to be elongated prismatic in habit with characteristic striations along the c-axis.

Properties

Refractive indices run from 1.62 to 1.65 with a birefringence of 0.018 to 0.022. Specific gravity is 3.05 to 3.10. Hardness is 7 to 7.5 on the Mohs scale. Pleochroism is strong in coloured material and is the principal challenge for the cutter, who must orient the table perpendicular to the c-axis to avoid the dark axial colour. Inclusions tend to include hollow growth tubes parallel to the c-axis, two-phase fluid inclusions, and trichites.

Treatments

Pink and red Kunar tourmaline is routinely heat-treated at modest temperatures (typically 500 to 650 degrees Celsius) to remove residual brown component and improve saturation. Green and blue stones may also be heated to lighten over-dark material. Heat treatment of elbaite is generally considered stable, undetectable in routine testing, and is not separately disclosed in most retail contexts beyond the standard assumption that pink and red elbaite has been heated. Irradiation is also used on some pink material to produce or intensify red colours, though the resulting colour stability requires verification.

Trade

Most Kunar production is sold through Peshawar in Pakistan and Bangkok. Stones range from accent sizes to large clean rubellites and indicolites in the multi-tens of carats. Pricing follows colour, clarity, size and cut quality on the standard tourmaline grading parameters; rubellite of saturated red without overtone of brown commands the highest premium, alongside neon-blue indicolite of Paraíba-style saturation (although Kunar is not a Paraíba source and the term should not be used).

Significance

Kunar is one of the world's most consistent suppliers of fine elbaite, alongside Brazil (Minas Gerais), Mozambique, Madagascar and Nigeria. Material from the deposit appears regularly at major trade shows and is a staple of mid- to high-quality commercial tourmaline jewellery in the international market.