When local fisherman snagged Chinese ceramics in their nets off the coast of Indonesia in 2003, it led to the discovery of a shipwreck that occurred more than 1,000 years ago. After excavations in 2004, the cargo of the “Cirebon Wreck”, named for the nearby town, was brought to the surface, with some surprising discoveries.
An estimated quarter million pieces were recovered from the 10th century merchant cargo ship, mostly ceramics, gold and silver items, knives, Hindu and Buddhist religious objects, and glassware. And, among this precious cargo were 400 Ceylon sapphires, thousands of garnets and zircons, large quantities of lapis lazuli and quartz, and jewellery made with Sri Lankan sapphires and Indian diamonds.
The director of the GIA Research Center in Bangkok, Ken Scarrett, was asked to examine the stones and determine their origin. He estimated that the garnets, zircons, and quartz were from Sri Lanka or South India and the lapis from Afghanistan. As for the 400 sapphires, ranging from blue to yellow to pink, he concluded that they were from the gem gravels of Ceylon (Sri Lanka). Also fascinating, he confirmed that, even after more than 1,000 years, the gem material coming out of the alluvial gravels in Sri Lanka today is the same as it was then.
Sapphires were already known in the 2nd century on the island, and by the 4th and 5th century, active international trade was taking place. Its sapphire mines are thus considered the oldest in the world. So, where are Sri Lanka’s sapphire mines? The answer was demonstrated for those of us who joined the ICA mine tour in May, following the ICA Congress in Colombo.
Geology and gems
The oval-shaped island of Sri Lanka is located a little to the east of the southernmost point of India. Measuring 402 km long and 224 km wide, on average, it is composed of pre-Cambrian metamorphic rock, divided into three major complexes: Highland, Eastern and Western Vijayan, and Southwest group. Most of the gem mining areas are in the Highland complex, a belt that runs from the base of the island through its centre to the northeast. The gemstones are found mostly in alluvial deposits, which are composed of gravels that have been carried down from the mountains and deposited in the flood plains of rivers and lakes. Since these are also agricultural lands, primarily rice paddies, the government has set strict rules for the dual-purpose use of the lands, which must be restored to their original condition after mining ceases.
There are now around 6,000 active mining operations in Sri Lanka, with some 40,000 men working underground daily. (Women and children are not allowed to work in the mines to avoid exploitation—the life of a miner is already difficult.) Recent laws prohibit mechanised mining so all mines must now be artisanal, which means that the only tools permitted are picks, shovels, spades, and baskets. Licenses are required for all activities, regardless of size. On our trip, however, we did see some mechanised operations whose permits predate the current law, but which may continue until their licenses expire.
Ratnapura – City of Gems
The gemstone centre of Sri Lanka is Ratnapura, or ‘City of Gems’ in Sanskrit. The nation’s main source of gemstones, this area produces many colours of sapphire, including the orange-pink ‘padparadscha’, as well as ruby, and cat’s-eye, among other gems. Mines, both shallow and deep, dot the landscape, mostly in rice paddies.
The methods of recovering gemstones have not changed over the centuries. Because the gem-bearing gravel is below the top layers of soil, miners drive a long pole into the ground to find the gravel layer, which can occur from a few meters to more than 30 meters. In the deeper mines, a shaft is constructed and reinforced with planks. In nearly all mines, water seepage is a problem and must be continually pumped out. After the gem-bearing material is brought to the surface, either by hand or hoisted up the shaft, it is washed in shallow baskets to sort out the gems.
The mining activities in the region have also given birth to a lively gem market, as well as cutting, heating and treatment facilities. Consequently, the population of Ratnapura has risen sharply over the last few decades. By law, however, foreign companies may not participate in trading or mining, and can only export stones that have been cut and polished in Sri Lanka.
River mining
In the Ratnapura district, the We Ganga and Denawaka Ganga rivers are well known for river mining. In this process, miners construct a brush dam where the water flow is slow and gem minerals concentrate. Long-handled scrapers are used to scoop up the gravel from the riverbed. The concentrate is then put into baskets to separate the gems.
Sri Lanka’s National Gem and Jewellery Authority is now engaged with the private sector to encourage ethical mining projects that use divers to collect gravel that has accumulated between the rocks at the bottom of the river. This method is seen as more environmentally friendly than other forms of river mining. Meanders in the river are often the most productive for finding gems.
Elahera gem fields
The nation’s second largest mining region, the Elahera gem fields account for 35 percent of the nation’s gem exports, and is located in the north-central part of the island. Although mining dates back to the 12th century, commercial operations began only in the 1960s.
Typical of residual types of gem beds, the deposits are primarily along the Kalu Ganga and Aban Ganga river systems, and include blue sapphire and ruby, as well as chrysoberyl, garnet, spinel, tourmaline, and zircon. Over the last 60 years, a number of large sapphires have been reported. Interestingly, bones and teeth of terrestrial mammals and fossilised wood have also been found in the gem gravel layers.
With some of the world’s most famous sapphires coming out of the island, such as the 563-carat Star of India and the 423-carat Logan Sapphire, we wonder what will be the next amazing sapphire to come out of the mines in Sri Lanka.
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