13 September 2011 Last updated at 06:43 ET

Royal wedding 'boosts Sri Lanka sapphire sales'

By Charles Haviland BBC News, Colombo

The sapphire was first worn by Princess Diana

Sri Lankan gemstone dealers say demand for blue sapphires has risen strongly since Britain's Prince William married Kate Middleton in April.

They say the stone in the bride's ring, previously worn by Princess Diana, originated in Sri Lanka.

In the first half of this year, Sri Lankan gem exports rose 35% over the past year to be worth more than $48m.

An ordinary sapphire can cost $17,000 per gram, as the gems are difficult to mine.

Gems from Sri Lankan pits include rubies and so-called cat's eyes - but the best-known are Ceylon Sapphires, above all the blue ones, although there are also yellow and pink gems.

'Prestige'

The Sri Lanka Gem and Jewellery Association has said it is beyond doubt that the sapphire in Kate Middleton's engagement ring, came from Sri Lanka more than three decades ago.

Sinan Salahudeen says there has been a rush for sapphires

However, earlier this year the royal jewellers, Garrard, declined to comment to the BBC on its origins.

A dealer at the 21st annual Gem and Jewellery exhibition in Colombo says the royal wedding has made stones like it very popular.

"There's been quite a rush here, especially for sapphires," said Sinan Salahudeen.

"It's something great that she's wearing a Ceylon Sapphire. That brings a lot of value to the stone and it's a prestige to our country as well."

'Cheap'

Gem pit owner Udaya Angammana said the cost of sapphires was not expensive given the difficulties of mining them.

"The way they are mined, the time it takes, the cost it takes to mine a pit - the stones are tremendously cheap," he said.

"I've got two pits. And one of the pits has only yielded about 30,000 rupees for the last entire month."

Blue sapphires are highly prized

That is less than $300 yield in a pit employing six men.

While some older pits have dried up completely, the gem industry is still able to satisfy international markets.

After a severe dip in exports, due to the world economic recession, the Sri Lanka Gem and Jewellery Association has said those markets are again growing healthily.