The truffle is a luxury fungus that's become a delicacy in French gastronomy. Being a truffle farmer requires years of patience and hunting for the "black diamond" cannot be done without the unrivalled sense of smell of man's best friend. Today, France produces almost half of the 120 tonnes of truffles sold throughout the world every year, and truffle lovers are prepared to pay up: some black truffles are worth as much as €1,000 per kilo. FRANCE went to sniff out its secrets.