Sri Lanka's Ratnapura City lies in a valley known for inspiring stirring myths and legends. For it was here, as told in the tales of the Arabian Nights, that Sinbad the sailor found a valley littered with gems. For 2,500 years, this has been the centre of Sri Lanka's gem industry. It is one of the richest gem-bearing deposits in the world. The gem industry provides a lifeline linking towns across the valley.

PROFESSOR DAYANANDA DILIMUNIA, GEM EXPERT: All type of gems, except for diamond and emerald, all types of gems are found, especially sapphires, spinels, garnet, cat's eyes, Alexandrite, all these things are found here.
For centuries, the miners of Ratnapura have searched the alluvial plains and water courses that run through this valley in search of precious and semiprecious stones. Traditions and work practices have changed little over that time. Mechanised mining is banned, a move aimed protecting a finite resource while minimising harm to the environment. Here gem-miners work side by side with those trolling for sand to sell. But it's underground that the greatest rewards lie.

MINER ON PHONE (Translation):Take the ones you've dug up.
With that, comes risk.

KKNIHAL JAYATILAKA, MINE OWNER (Translation): This mining is a very dangerous job. This goes down and along about 120 feet. There's a lot of risk for the workers. That's what I can tell you.
After a tunnel collapsed, injuring one man, this mine almost shut down. A decision was made to send for a new foreman with special talents. Surat is that man. When Surat arrived, his first task was to help the miners on site to overcome their fear.

SURAT, MINE FOREMAN (Translation): Our group got really scared when they saw how deep the hole was. As I was wondering how to work with them, one was brave enough to get into the hole. After going in and out, he got used to it. I was happy there was at leat one person to support me. That's how I started work on this.
A miner since he was a child, Surat's speciality is safety. He knows how to prop up a mine to prevent tunnels collapsing. Here in the paddy fields, where the water table is high, his talents are in strong demand.

SURAT (Translation): The mine is hard to work in the rainy season. Water seeps in, it breaks up and it's hard to fix. So it's very hard work. In the dry season, it was quite easy but it's getting hard again. We won't give up, we'll do it somehow.
Mining here is home to an ancient work principle - that of collective work. One in, all in - everyone involved takes a cut in the Democratic Socialist Republic of Sri Lanka. The profits from this mine are divided amongst all who work here or contribute to its success. It's an ages-old practice, almost as old as mining here itself.

KKNIHAL JAYATILAKA (Translation): After we find the gems, we put them up for auction. Of the money from the auction, the first 20% goes towards the engine and the diesel. The next 16% goes to the mine. The next 6.4% is for the licence. The rest is divided between the manager and eight others. It's divided by ten. Two parts go to the overseer and the remaining eight parts go to the other workers.
When it comes to valuing what lies below, Surat says he has no favourites.

SURAT (Translation): There is no such thing as my favourite gem. What brings the most money that's what I like.
And that's what this is all about - secret men's business of sorts. This is Ratnapura's rough stone market, where uncut gems are bought and sold, and fortunes made or lost.

JEWELLER (Translation): It's small. Around two-and-a-half.
It pays to travel with an expert. Professor Dayananda Dilimunia is such a man. He's one of Sri Lanka's foremost gem experts. This on-site valuation revealing a potential trap for those not in the know.

PROFESSOR DAYANANDA DILIMUNIA: This is worth 1,000 rupees, he says.

REPORTER: Is it?

PROFESSOR DAYANANDA DILIMUNIA: No, this stone is flat, so there is no brilliance. There is likely. The other thing is, the colour is patchy. You have a blue match on one side. But still we can bargain. The price what they say, we can come down.

REPORTER: What would you pay?

PROFESSOR DAYANANDA DILIMUNIA: I would ask for less than, say, 200 rupees.

REPORTER: From 1,000 to 200?

PROFESSOR DAYANANDA DILIMUNIA: Yes, because this has no brilliance, only the colour.
The speculation here is whether the money paid out for a rough stone will return its value once it's cut.

BHADRA MARAPANA, JEWELLER: They buy a stone, then they sell, they get a little money, they buy again. You know, it goes on like that. Sometimes they win, sometimes they lose. It's a gamble also.
Thousands have been won and lost in this daily ritual. But there are some certainties, although only at this end of the business.

BHADRA MARAPANA: Well, for people who buy cut and polished stones, there is no risk. Only those who deal with the rough stones have the risk. But then if you buy a cut and polished stone, you never lose. It's like buying a material like a suit, it's already finished.
Bhadra Marapana is an artist. Myths and beliefs about the healing qualities of gems form the basis for his creations.

BHADRA MARAPANA: This is a bangle with all Sri Lankan stones - sapphires, cat's eyes, rubies, pink sapphires, orange sapphires, spinels, garnets.
While myths may well be the stuff that legends are made of, Bhadra warns against taking them too seriously.

BHADRA MARAPANA: People they see their horoscopes and they are asked to wear such and such a stone. So normally they go into that, you know, because they need some sort of consolation.

REPORTER: So it doesn't necessarily work, but it makes you feel better?

BHADRA MARAPANA: Exactly. I think it's something like that.
And the gem-miners of Sri Lanka are more than happy to live with that myth.