Gem-mining is primitive and dangerous; miners dig a circular hole about 1m in diameter and as deep as 10m, without any internal supports or reinforcement, and with only candles for light. As the miner goes deeper, the earth is hauled to the surface in a wicker basket using a variety of low-tech winches made of bamboo and rope. A series of small steps are dug in the wall so that the miner can climb out. The main gemstone found in the area is semiprecious zircon, which looks like brown glass in its raw state but turns pale blue when heated. Also found in Rattanakiri are yellowish green peridot, pale purple amethyst, clear quartz and shiny black onyx.
The sites where gems are mined in Rattanakiri province change regularly, so it’s best to check in Banlung before setting out to look for them. Most activity currently centres around Chum Rum Bai Srok, in Bokeo district. There’s not much to see – once you’ve seen one mining pit, you’ve seen them all – but the 35km trip from Banlung is interesting for the scenery, the awfulness of the track and for the sheer exhilaration of having made it. The gem-mining camp is difficult to find without a guide (around $15–20/day; ask at your guesthouse) or a good command of Khmer. South of Ka Chhang, the road soon turns into a narrow churned-up track that winds up and down valleys and forks off left and right through encroaching jungle, until it deteriorates into an even narrower rutted path. If it starts to rain, the track can become impassable and visitors have had to spend the night in the site’s blue-tarpaulin-covered shacks.