Petra Diamonds’ rough prices decreased at its first tender of the fiscal year as the anticipated pickup in demand proved disappointing.

The August trading session brought in $79.3 million from the sale of 696,194 carats, with like-for-like prices — those for similar categories of diamonds — falling 4.3% compared with May, the miner reported Friday.

The slowdown was primarily due to flagging prices for rough between 2 and 10.8 carats, which dropped 14% on a like-for-like basis. Prices for diamonds under 2 carats rose 1% to 2%, Petra noted.

While the tender saw strong attendance, “demand was more muted than we had expected in exiting the summer holiday period,” explained Petra CEO Richard Duffy. “The expected seasonal improvement in demand was evident for higher-quality 10.8-carat-plus stones, with solid prices realized. [However,] this was offset by slower demand for 2- to 10-carat size ranges.”

The miner did not sell any exceptional stones during the tender, it reported, though it did garner $1.7 million for a 20.9-carat yellow diamond from its Cullinan deposit.

Overall sales value rose 88% from May’s $42.1 million but slid 23% from the equivalent tender a year earlier, which took place in September 2022. Sales volume was up 49% from May and 34% year on year, while the average price jumped to $114 per carat from the previous tender’s $90.

Main image: Ore processing at the Williamson mine. (Petra Diamonds)