Bold caption. [Nikolay Doychinov/AFP]

The painstaking process involves hours of wading through rivers, digging and panning to find "a spot", he explains.

"Gold is 19 times heavier than water and harder to move along the curves of the river so we seek in the gravel along the turns, near tree roots, under big stones or inside cracks in the rocks," Stamenov explains.

"We examine the specks under a magnifying glass: if they are rounded it means that the river has dragged them many kilometers, if they are sharper, the vein must be nearer," he adds.

If from one cubic metre of gravel - corresponding to 400 spadefuls or 100 buckets - panners get 0.5 to 1.0 grams of gold, the vein is worth being explored.

For 50-year-old electrician Hristo Atanasov, the search matters more than getting lucky.

"It is tiring if you put your mind to finding gold at any cost but if you think about it as something that will help you forget the daily worries, it is a priceless pastime," he says, sipping a beer.