The world’s largest diamond mining company, De Beers Group, has postponed its fifth and sixth sales cycle auctions for the year amid concerns about dwindling international demand.

The fifth sight is scheduled for 5-9 June and the sixth on 10-14 July. In a statement, the company said the interim and main auctions will be combined into a single event.

"After careful consideration and analysis of the current market situation, we decided to combine both cycle 5 and 6 interim and main auctions,” the statement reads.

"While this was a difficult decision to make, we believe that it is one that reflects our sustainable and responsible approach to rough diamond supply."

According to reporting by IDEX, declining demand from Indian manufacturers paired with slowing consumer demand in the US and China prompted the decision.

Research from Tenoris reveals that in the US in April, natural diamond jewellery sales declined by 19.3 per cent year-on-year.

“In the sports world the term ‘career year’ is used to describe that one-time anomaly where an athlete performs well above expected levels. April 2022 was the end of the [diamond] industry’s career year,” writes Edahn Golan.

“Prices of natural diamonds rose overall in April. And yet, this did not offer the kind of relief diamond traders or retailers were seeking in the last few months.”

He added: “The news that requires attention is that the number of diamonds sold and the total value of sales have completed a year of year-over-year declines. Retailer gross margins, which climbed through most of 2022, have declined every month in 2023.”

De Beers’ most recent sales cycle concluded on 5 May, achieving sales of $US480 million ($AU722.6 million). 

More than $US540 million ($AU805 million) in sales were completed in the third cycle in early April, with CEO Al Cook noting many encouraging trends at the time.

While the decision to postpone the upcoming auctions may be surprising, it’s not unprecedented. In 2020 De Beers cancelled planned rough sales in March due to the impact of the COVID-19 pandemic.