Pailin
Pailin
The Cambodian province that supplied Southeast Asian sapphire and ruby for centuries
Pailin is a province in western Cambodia, abutting the Thai border at the southwestern flank of the Cardamom Mountains, and historically one of the most important sources of sapphire and ruby in Southeast Asia. The Pailin gem fields supplied the Bangkok cutting trade and through it the international market with substantial volumes of corundum from at least the early twentieth century, with periods of intensive working alternating with periods of disruption tied to the long Cambodian conflict from the 1970s through the early 1990s. Production is now greatly reduced, but Pailin remains a recognised origin term in the corundum trade and a benchmark for a particular style of Cambodian sapphire and ruby.
Geological setting
The Pailin sapphire and ruby occur in alluvial gravels derived from weathered alkali basalt flows, in geological terrain comparable to the Bo Rai and Chanthaburi deposits across the border in Thailand. The basalts erupted in the late Cenozoic, and the corundum crystallised at depth from the host magma before being brought to the surface as xenocrysts. Weathering of the basalt and erosion into the local drainage system concentrated the corundum in the alluvial gravels, which are worked by hand and small-scale mechanised methods.
The Pailin sapphire
Pailin sapphire is best known for a saturated, slightly violetish-blue colour traded in the historical literature as a Cambodian or Pailin cornflower blue, although the term is used loosely and the actual colour distribution covers a range from medium-light blue through to a darker inky blue. The finest stones show a clean, even blue with strong saturation and good transparency. The basalt-related origin gives the material the iron-rich chemistry typical of Southeast Asian sapphires, with the consequent slight tendency toward darker tones and the characteristic absence of the silk inclusions associated with the metamorphic-origin sapphires of Sri Lanka and Kashmir.
Heat treatment is routine for Pailin sapphire, with conventional heating used to clarify silk and to optimise colour. Beryllium diffusion is not characteristic of Pailin material in the same way as for some other Southeast Asian sources.
The Pailin ruby
Pailin also produces ruby, with strong red colour and moderate to good transparency from the better-grade material. The volumes of ruby production from Pailin are smaller than the sapphire production but the material has had a long-standing presence in the Bangkok cutting trade and competes in the market with Thai and other Southeast Asian rubies.
Production history and the conflict period
Commercial gem mining at Pailin developed in the late nineteenth and early twentieth centuries under the French colonial administration, with French and Burmese-Shan miners and traders developing the cutting and export trade. Production peaked in the third quarter of the twentieth century. The Cambodian conflict from 1970 onward, and particularly the Khmer Rouge regime of 1975 to 1979, severely disrupted gem mining, although the gem fields became an important source of revenue for the Khmer Rouge in the years that followed when they retained control of the area into the 1990s. The province was not fully reincorporated into the central Cambodian state until 1996.
Production declined sharply in the 1990s and 2000s as the most accessible alluvial deposits were worked out, and the modern Pailin output is a small fraction of historic levels. The province now functions principally as a regional gem-trading centre rather than as a major source of new rough.
In the trade
Pailin is a recognised origin in the contemporary corundum trade, although the volume of fresh material is much smaller than during the peak production era. GIA, AGL, and the European laboratories will issue Cambodian or Pailin origin opinions where the data support the determination, although origin determination at the Pailin level is less commercially significant than for the great historic origins. Most material described as Pailin in the modern market is older stock or stones cut in the Bangkok trade decades ago.