Ceylon Sapphires

Sri Lanka has been linked with gemstones for a very long time. The National Gem and Jewellery Authority (NGJA) records that the island was once called Rathna-dweepa, the island of gemstones, a name found in many chronicles. It also cites the Mahavansa, the historical chronicle of the island, which refers to its wealth in gems.

Foreign writers noticed the same thing. The Authority quotes Marco Polo, whom it dates to 1292, writing that rubies, sapphires, topazes, amethysts and garnets came from the island's streams. The Export Development Board states that some of the island's mines reach back to the second century AD and that trade in its sapphires is recorded in the fourth and fifth centuries. The Authority names the blue sapphire as the national gemstone.

Sapphire and ruby are the same mineral. Both are corundum, a crystalline form of aluminium oxide. The NGJA notes that the gem trade did not know this until 1802, when chemical analysis showed that the two stones were varieties of one mineral.

Colour comes from trace elements. According to the Authority, titanium and iron give sapphire its blue, while chromium gives ruby its red. Pure corundum is colourless. Sri Lankan sapphires are also found in yellow, pink, green, violet and other colours. One variety, padparadscha, combines pink and orange. The Export Development Board explains that its name comes from padmaraga, a Sanskrit term for the lotus blossom. Sapphire has a hardness of 9, one step below diamond.

Most Sri Lankan gemstones are not cut from hard rock. The NGJA explains that they occur mainly in alluvial gravels in valley bottoms. Streams carry gem minerals down from weathered rock on hilltops and hillsides and leave them in the gravel.

The Export Development Board states that large areas of these deposits have been mined in the Ratnapura and Elahera gem fields, where the majority of coloured gemstones are found. Blue sapphires come mostly from alluvial deposits in the part of the island that geologists call the highland complex. Rough sapphire from the Elahera region has a strong reputation for quality, and new deposits have been found in the Kataragama area. The Authority states that around 75 varieties of gemstone have been mined or found in Sri Lanka.

Not every stone comes out of the ground with good colour. The Export Development Board records that Sri Lankan gem cutters have used heat to correct uneven colour since ancient times. The stones were once treated at charcoal hearths with the help of blowpipes. Today they are heated to more than 1,000 degrees Celsius with modern burners.

A local term belongs to this craft. Geuda, the NGJA explains, was first used in Sri Lanka for corundum with a milky or cloudy look. Heat treatment can turn geuda into transparent sapphire. The Authority estimates that about 35 to 40 per cent of the corundum mined in Sri Lanka could be classed as treatable geuda, and notes that deposits of it are widely spread within the island.

Several large stones are traced to Sri Lanka. The NGJA lists the Blue Giant of the Orient at 466 carats, the Logan Blue Sapphire at 423 carats and the Blue Belle of Asia at 400 carats. The Star of Sri Lanka, at 393 carats, is held by the Authority itself. The Authority also records that the engagement ring given to Lady Diana Spencer held a 12 carat oval Ceylon sapphire surrounded by 14 diamonds.

A state body has been responsible for the trade since 1971, when the State Gem Corporation was established on 1 November. In 1993 it became the National Gem and Jewellery Authority, with the task of developing, regulating and promoting the industry. The Authority notes that Sri Lanka was known as Ceylon until 1972. The older name remains in use for its sapphires.