Brands come up with creative designs to add value to their gems

They lied. It seems diamonds are not, in fact, forever. Existing stone mines around the world are being depleted, and as a result, precious stones are becoming ever more elusive and prized. You wouldn't expect the jewellery market to complain - after all, a market where supply is limited and demand grows ever higher sounds like a recipe for success.

Nevertheless, industry experts reveal that it's not all smooth sailing, and that innovation and creativity are more important than ever as brands seek to entice increasingly educated consumers with their high jewellery creations.

The figures are certainly impressive. According to De Beers Group, the market saw an annual growth rate of 18 per cent from 2008 to 2013, with China seeing the world's fastest spike in diamond and jewellery sales over the past decade.

"What we're seeing is that the prices paid for diamonds have risen 32 per cent in the past two decades, and the average carat count of each piece has risen from 18 points to a quarter carat [around 23 points]," says Stephen Lussier, the executive vice-president of the group's marketing department.

The problem, however, is that stone supplies are dwindling. "The stock is just not there," says Thierry Robert, stone purchasing director for Boucheron.

"Even if you had no [limit to your] budget and came to me asking for two matching rubies for a pair of earrings, I would say 'keep your money'," he says, explaining that he simply could not guarantee that he would find two matching stones within a reasonable time. "The problem is that there isn't much left in old mines," he says. "New mines aren't as nice - the brilliancy of the stones isn't quite as pure."

Quality aside, finding new mines in the first place is far from easy, says Bruce Cleaver, the executive head of strategy at De Beers Group. "As the existing mines are ageing, it is extremely difficult and costly to find new ones and make them operational," he says, pointing out that the group spends around US$50 million a year on worldwide exploration for new mines.

The company also has the latest technology to help with the process - a superconducting quantum interference device (SQUID), which locates diamond deposits by detecting subtle changes in magnetic fields. Even on discovering a new mine, however, it's no guarantee it'll pay out.

"Of the last 140 years, around 7,000 mines were discovered … but only one in seven actually produced diamonds and, among these, only 60 were sufficiently rich in diamond content to make them economically viable. And of these again, only seven became what we can call a tier one mine," Cleaver says.