Kohistan peridot, also referred to as Pakistan peridot or Sapat peridot, is gem-quality peridot mined from the Sapat Valley of the Kohistan region in Khyber Pakhtunkhwa Province, Pakistan, at altitudes of approximately 4,500 metres in the western Himalaya. The deposit was discovered in 1994 and worked through the late 1990s and 2000s, producing a flow of large, exceptionally fine-coloured stones that displaced Burmese and Arizona peridot at the high end of the trade for several years.

Geological setting

The Kohistan peridot deposit lies within the Kohistan island arc, a Cretaceous oceanic terrane caught between the Indian and Eurasian plates during the Himalayan collision. The host rock is dunite, a coarse-grained ultramafic rock composed almost entirely of olivine, the mineral species of which peridot is the gem variety. The Sapat occurrence is hosted within a serpentinised dunite body that has yielded large euhedral crystals to ten centimetres or more, with iron content low enough to produce the strongly green colour favoured in fine peridot. The deposit was worked seasonally because of the high altitude and the difficulty of winter access, with the principal work concentrated in the summer months.

Appearance and quality

Kohistan peridot is distinguished by its vivid, saturated green colour, often with a slight yellowish secondary, and by its remarkable size range. Faceted stones above ten carats are routinely available from this source, and stones above twenty carats appear with regularity. The colour at the top end of the production rivals or surpasses fine Burmese peridot from the Mogok and Pyaung-gaung deposits and is more saturated than the typical Arizona San Carlos production. The crystals tend to be cleaner than peridot from other sources, with lower densities of the lily-pad inclusion characteristic of Burmese material, although chromite and ludwigite inclusions are present in some stones.

Identification

Identification of Kohistan origin in faceted peridot rests on the inclusion suite. The GIA, SSEF and Gubelin laboratories have published origin determination criteria distinguishing Kohistan from Burmese and Arizona stones on the basis of the proportion of various inclusion types, the trace-element profile measured by LA-ICP-MS, and certain growth-zoning patterns. The trace-element distinction is generally reliable; the visual distinction is supportive but not always conclusive on its own. Origin reports for fine peridot are now routinely requested for stones above five carats, and Kohistan origin commands a modest premium over equivalent Burmese material in the contemporary market.

Trade position

Production from the Sapat deposit has slowed since the late 2000s as the most accessible workings were exhausted, with the peak years generally cited as 1995 to 2005. Stones in the trade today are a mixture of recent production and inventory accumulated during the peak. Pakistan peridot at fine quality remains one of the principal sources for matched parcels and large stones, alongside the Burmese revival of recent years and the long-running Arizona production. For Toronto buyers, Kohistan peridot represents the cleanest available large-stone option in the species, and is the source of choice for matched bracelet and necklace projects where colour and size consistency are required.