Colombia produces more than half the world's emeralds; it is excruciatingly hard work, and in Muzo, entire families sweat it out in extreme conditions hoping to find the stone that will change their lives.

At 19, Adrian is a veteran, having been brought to work by his parents for years already, he said.

"This is something you do from the time you are a little kid. Then when you are about 15, you start doing the really hard physical work," he said, smiling, caked in dirt head to toe, outside the La Espanola mine in Boyaca department.

Workers -- including lots of father-son teams -- swelter in tunnels where the temperature hovers around 40 degrees C (104 F), for eight-hour shifts, with a breathing piece on their mouths and a light on their helmets.

The tough slog and safety gamble is not for the minimum wage ($320 a month) they earn. These people are mining dreams, just as they are mining gems.

"You see, that is what we are really after when we come down the mine. You don't come for the salary. You come because you are hoping you find an emerald that will be your ticket to retirement. If you find a really significant one, you might not have to keep working," explained Adrian.

"I have seen a lot of accidents. It is usually when somebody is overconfident," he added, explaining that while he has not been seriously hurt, he did get dizzy spells in the long shafts when he was starting out.

"In the end, you have to be careful. But you also have to remember that life is short, and you have to make the most of it," added the young man, who has lost at least one close friend in mining accidents.

Mining accidents have not been the only cause of fatalities in the industry.

For decades, fighting for control over, and access to, what are believed the most lucrative emerald mining areas has fueled what is locally known as "The Emerald Wars".

About 3,500 people were killed in fighting between 1984 and 1990, alone, according to government estimates, and it took a peace agreement to quiet the region down.

Colombia currently produces about 55 percent of the world's emeralds -- about 3.4 million karats. Exports of Colombian emeralds have been worth around $130 million a year for the past five years, with India the leading buyer, followed by the United States and Thailand, the National Emerald Federation says.

-- China, gem of an emerging market --

Miners all know that the real business is in exports. And that has been the guiding light for emerald-mad Alberto Sepulveda, who owns several Colombian mines.

At the 2010 Expo Shanghai jewel and gemstone fair, Sepulveda was the only man standing to represent Colombia and open a vast potential new market for the stones.

Even with trade challenged by tough economic conditions, China's taste for a quality product is set to make it a big buyer, he said, and Colombia is poised to take advantage.

"Colombian mines are really still at the near-virgin stage, not even 10 percent of known reserves have been mined. So we have the opportunity to sell a lot," Sepulveda, who has been in the business for four decades, said.

"And we are going to need them, because China is starting to buy them, and is shaping up as a very interesting market."

As he sets his sights on Asian markets, Sepulveda is also working to cement Colombia's spot as the world leader on emeralds, opening the world's first museum dedicated to the dazzling green gems.

His museum, which opened earlier this year and boasts more than 3,000 exhibits, aims to highlight the best and brightest gems in this South American nation. They are often lighter or almost milky green when uncut and take on deeper tones after getting their glinty facets.

The exhibits here in Bogota demonstrate Colombia's best gemstones from Muzo, Coscuez, Chivor and Gachala, which Sepulveda said were coveted by buyers in China, the United States and Italy.

"Colombian emeralds are the best in the world," he said. "So these are top-quality stones, in larger sizes. They really cannot be matched anywhere else."