De Beers, the diamond miner which acts as the canary-down-the-mine for the ultra-luxury goods sector, yesterday sounded a warning call that the party may be coming to an end.
The miner, which produces about 40 per cent of the world's rough diamonds, reported a bumper year for 2011, with profits soaring by nearly a half to $1.47bn (£805m) despite concerns about the global economy.
The average diamond price jumped 29 per cent over the year, as wealthy customers in China and America rushed to spend their cash on precious stones.
This pushed up sales at De Beers' trading arm by 27 per cent to $6.5bn, their second-highest level ever.
But 2011 proved a year of two halves, with the first notably better than second as concerns about the eurozone gathered momentum.
"During the second half, both retail and cutting centre sentiment was impacted by the challenging macro-economic environment... and a slowdown in the rate of growth of consumer demand at retail," a De Beers spokesman said.
"As a result, during the latter part of the year, De Beers experienced lower levels of demand for its rough diamonds and prices receded slightly from the highs seen in the middle of the year," he added.
But he claimed any slowdown would be slight and temporary.
"In spite of uncertainty, and barring a global economic shock, we expect to see continued growth in global diamond jewellery sales, albeit at lower levels than the exceptional 2011 growth," he said.
"In the medium to longer term, the industry fundamentals remain positive with consumer demand, fuelled by the emerging markets of China and India, outpacing what will likely be level carat production."
In November, FTSE 100 mining group Anglo American, which already owns 45 per cent of De Beers, signed a deal to acquire the Oppenheimer founding family's 40 per cent stake for $5.1bn.
The deal, expected to close later this year, will give Anglo American control of the company, leaving the government of Botswana as the only other significant shareholder.