Polonnaruwa is a district in the north-central dry zone of Sri Lanka, historically the medieval royal capital of the island and now an active gem-mining area producing alluvial sapphire, garnet, and a range of secondary gem species. Less internationally famous than Ratnapura and the southern wet-zone gem fields, Polonnaruwa nonetheless contributes a meaningful share of Sri Lanka's coloured-stone production and is documented in gemmological literature as a distinct geographic source within the broader Sri Lankan trade.

Geological setting

The Polonnaruwa district sits within the Highland Complex of central Sri Lanka, one of the three high-grade metamorphic terrains that comprise the island's basement geology. The Highland Complex is the host for most of Sri Lanka's primary gem mineralisation, including sapphire, ruby, and the associated suite of garnets, spinels, and beryls. In the Polonnaruwa area, the gem-bearing rocks are eroding into seasonal stream and floodplain gravels — the alluvial deposits known locally as illam — which constitute the working medium for the district's gem mining.

The dry-zone climate of Polonnaruwa, with a long dry season punctuated by a shorter monsoon, structures the rhythm of mining: the heaviest work is concentrated in the dry months when river beds are exposed and pit walls remain stable. Mining is predominantly small-scale and artisanal, with shallow shafts sunk into illam terraces and gravels processed by the traditional methods of pan and rocker.

Gem species produced

Sapphire is the principal product, with the typical Sri Lankan range of blue, yellow, pink, and the orange-pink variety known as padparadscha. Polonnaruwa sapphires share the optical character of broader Sri Lankan production — the lighter, more transparent body colour that distinguishes Sri Lankan sapphire from the saturated Burmese and Kashmir material — and are commonly heated to develop colour for the international market. Garnets from the district include hessonite, the orange-brown grossular variety historically associated with Sri Lankan production, and spessartine, the orange manganese-rich species. Smaller production includes spinel, zircon, tourmaline, and topaz.

History and trade context

Polonnaruwa was the political and cultural capital of Sri Lanka from the eleventh to the thirteenth centuries, and the district holds substantial archaeological remains from that period that are now a UNESCO World Heritage Site. The gem trade in the area predates and survives the political shifts; Sri Lanka has been a continuous source of gemstones for at least two millennia, with mentions in classical and medieval trade records.

Modern gem mining in Polonnaruwa is regulated by the National Gem and Jewellery Authority of Sri Lanka, which licenses miners and operates a system of licensed gem markets in the district capitals where miners and traders meet to transact. The district's production reaches the international trade primarily through the cutting and trading centres of Ratnapura and Colombo.

In the trade

Polonnaruwa-attributed sapphires and garnets are not generally distinguished by commercial buyers from broader Sri Lankan production; the country-of-origin attribution at Sri Lanka rather than at the district level is the standard for laboratory reports and trade documentation. Buyers with a specific interest in Polonnaruwa material typically work directly with miners or with regional dealers who track district-level provenance. The district's stones are otherwise indistinguishable in the international market from material from Elahera, Ratnapura, or other Sri Lankan sources.

Further reading

• GIA — Sapphire reference
• GIA Gems & Gemology — Sri Lankan gem production
• International Gem Society — sapphire localities