As the saying goes, "diamonds are forever", yet with rising production costs and shrinking demand from China - the second largest diamond market after the United States - the industry is in the rough.

More than 130 million carats or 26,000kg of diamonds are produced each year. Globally, there are natural diamond reserves - more than 600m carats - to guarantee another four years of production, with Australia, Russia, DR Congo and Botswana being the world's biggest producers. 

Last year, the "blue moon" diamond sold for a staggering $48.8m - a record for diamond sales. Despite this, 2015 was a bad year for sales with rough diamond inventory clogging up production pipelines.

We speak to Stephen Lussier, chief executive of De Beers retail arm Forevermark about why 2015 was a poor year for sales, how weaker global economic growth affects the demand for luxury consumer goods - diamonds are mostly sold as jewellery - and how diamonds are getting rarer as the global supply dries up. 

We also hear from Alain Vandenborre, founder of the Singapore Diamond Investment Exchange about the culture of trading diamonds - largely localised, manual and opaque - and an initiative to bring transparency to trading.

Also on this episode of Counting the Cost:

Thailand's modern-day gold rush: Although Thailand currently only has one operational gold mine, the country has the reserves for more to come. Thailand's sole mine is profitable with over $2.2bn worth of gold being poured in the past 15 years. But this mine is an important test for future operations with people saying the mining activities are poisoning their communities, and campaigning for the government not to renew the mine's licence when it runs out on May 13.

Turkish Airlines flies high: Turkish Airlines has become a global contender within the commercial aviation industry: In 2015, it reported a record profit of $1.7bn; in the first quarter of this year it flew 14.2 million passengers - that's a 10 percent increase for the same period last year; and it now flies to 285 places, making the carrier the fourth largest in the world by number of destinations. We speak to Temel Kotil, chief executive of Turkish Airlines, about its goals, how passengers have grown by 30 percent annually in the past decade, and the importance of an airline to a country's growth. 

Nigeria's property boom: Property investors in the Nigerian city of Maiduguri are benefiting from a rise in real estate prices following the retreat of Boko Haram fighters. Many of those now profiting bought houses at cheap prices from residents escaping the fighting. We visit one street where at the height of the crisis people sold their land for $1,000; that land now costs as much as 10 times that. Returnees are struggling to house themselves, with new owners refusing to sell back property at even double the price. 

Source: Al Jazeera