Pyaung Gaung is a peridot-bearing locality within the Mogok Stone Tract of Upper Myanmar, north-east of the township of Mogok itself. The deposit is best known to the trade for fine, vivid yellowish-green peridot of high clarity and strong saturation, and is one of the small group of producers — alongside Sapat in Pakistan and the San Carlos Apache reservation in Arizona — whose material defines the upper end of the peridot market. Pyaung Gaung material has been worked intermittently for at least a century and has supplied many of the historic large peridots in private and museum collections, including stones traditionally attributed to the historic gem trade of Lower Burma and the wider Mogok district.

Geological setting

The Mogok Stone Tract is a metamorphic terrain of marbles, gneisses, and skarns formed during the collision of the Indian and Asian plates. While Mogok is most famous for ruby and red spinel from its calcite-rich marbles, the region's geology also includes ultramafic bodies — peridotites and serpentinised peridotites — that host the peridot at Pyaung Gaung. Peridot is the gem variety of forsteritic olivine, (Mg,Fe)₂SiO₄, and forms in mantle-derived rocks where magnesium dominates the iron content. The Mogok peridot occurs in association with chromite, spinel, and accessory chrome-bearing minerals that contribute trace-element signatures used by laboratories for origin determination.

Crystals from Pyaung Gaung are typically transparent, well-formed prismatic individuals, occasionally exceeding 10 centimetres in length and yielding cut stones of 10 carats and well above. The largest documented Burmese peridots run into the hundreds of carats and reside in institutional collections including the Smithsonian and the American Museum of Natural History. The host rock is generally weathered and partly serpentinised at the surface; mining proceeds by following the peridot-rich lenses into less-altered material at depth, where the crystals retain better clarity and stronger colour.

Colour and quality

Fine Pyaung Gaung peridot exhibits a vivid yellowish-green to slightly bluish-green hue with strong saturation and only minor brownish secondary modifier. The colour is governed by iron content, with the most prized stones falling in a relatively narrow Fe range that yields green dominant over yellow without darkening into the olive tones of higher-iron material. Inclusions characteristic of the locality include lily-pad-shaped fluid discs, oriented chromite octahedra, and the so-called peridot-in-peridot intergrowth where compositional zoning produces visible internal structure. These inclusions are diagnostic and feature in the standard photoatlases used by laboratory gemmologists.

Clarity in fine Burmese peridot tends to be excellent — the material faces up clean to the unaided eye in stones up to 5 carats and frequently in larger sizes. The combination of strong colour, high clarity, and large crystal size makes Pyaung Gaung material distinct in the market from the more abundant but generally smaller and slightly less saturated peridot from Sapat or San Carlos. Pakistani Sapat material can rival Mogok stones in colour saturation but seldom matches the largest crystal sizes; San Carlos peridot is generally well coloured but smaller and less intensely saturated.

Cut Pyaung Gaung peridot favours classical step and brilliant designs; oval and cushion mixed cuts are common because they make the most of crystal habit while preserving weight. Faceting must accommodate olivine's strong birefringence, which can produce visible facet doubling in larger stones if the cutter does not orient the table relative to the optic axis with care.

In the trade

Burmese peridot of Pyaung Gaung origin commands a substantial premium over comparable material from other sources, reflecting both the perceived quality difference and the scarcity of new production. Mining at the deposit has been intermittent and small-scale; access has at times been restricted by political and security conditions, and supply to the international market has fluctuated accordingly. Stones in the global trade today are often older inventory or recut material rather than fresh production.

For pieces above approximately 5 carats with claimed Burmese origin and exceptional colour, a laboratory report from a recognised laboratory — Gübelin, SSEF, GIA, or AGL — is the standard expectation in the international trade. Laboratory origin determination relies on the trace-element signature, inclusion suite, and growth features distinctive to the Mogok ultramafic source. Stones without origin documentation tend to trade well below origin-confirmed Burmese material, even where the colour and clarity appear comparable in the loupe.

Identification and care

Peridot is identified by its high birefringence (about 0.036), refractive indices in the range 1.65 to 1.69, specific gravity around 3.32 to 3.37, and strong doubling visible through the table of any sizeable stone. Hardness is 6.5 to 7 on the Mohs scale — adequate for most jewellery applications but soft enough to require care in ring designs subject to heavy wear. Peridot is sensitive to thermal shock and acidic environments; ultrasonic and steam cleaning are not recommended, and warm soapy water with a soft brush remains the standard cleaning method.

The lily-pad inclusions characteristic of Pyaung Gaung material are typically harmless to durability but should be noted in any condition report. Larger fluid-filled cavities or healed fractures intersecting the surface can compromise structural integrity in ring use and warrant a protective setting style. For collector-grade stones above 20 carats, bezel or partial-bezel mountings are preferable to high-set prong work, both for security and for protecting the girdle during handling.

History and provenance

Burmese peridot has been traded since at least the medieval period, and many of the historic European church and royal collections contain large pale-green stones long described as "chrysolite" or "topaz" that modern gemmological examination has reidentified as peridot — frequently of Mogok origin based on inclusion characteristics. The Pyaung Gaung name itself entered the modern gemmological literature in the twentieth century as systematic mineralogical surveys of the Mogok district recorded the specific peridot-bearing localities within the broader stone tract.

Further reading

• GIA — peridot reference
• GIA Gems & Gemology — Mogok and Burmese peridot articles
• International Gem Society — peridot
• ICA — peridot trade information