Diamond imports and exports fell in June compared to promising results in April and May, according to Belgium’s diamond trading, suggesting the world diamond market is still too volatile to support hopes of strengthening or recovery.

The results come after May data showed Belgium’s first monthly increase in polished diamond exports in almost a year, Diamonds.net reported.

Orders from the U.S., Belgium’s No. 1 trading partner for polished diamonds, fell 4.7 percent, but the overall plunge was driven largely by a 17-percent drop in polished diamond shipments to Hong Kong, Belgium’s No. 2 partner.

Botswana is the world’s biggest producer of diamonds, which account for around 75 percent of its foreign exchange earnings and 30 percent of GDP, Reuters reported. The country slashed its 2015 growth forecast as a sharp drop in diamond prices hurt the economy. Read more about the top diamond producing countries in Africa.

Botswana’s state-owned Okavango Diamond Company saw a 35 percent jump in sales volumes in the first six months of 2016 compared to the same period in 2015 — signs of a global diamond market recovery, according to Mmegi, the national newspaper of Botswana.

“Prices today remain below where they were at the beginning of 2015,” said Toby Frears, managing director of Okavango Diamond Company.

Okavango Diamond Company, or ODC, was established in 2013 to market a portion of rough diamond production at Debswana, a mining company owned by DeBeers in Botswana that is the world’s leading producer of diamonds by value.

Botswana seeks to develop its own price book through an independent window outside of De Beers’ channels, Mmegi reported. ODC is entitled to market 15 percent of Debswana’s total run of mine production in 2016.

Despite weak diamond prices for the first half of 2016, strong sales pushed revenue up slightly at Africa-focused Petra Diamonds, according to Mining.com.

Petra operates four diamond mines in South Africa including the iconic Cullinan mine, and one in Tanzania.

The diamond firm attracted investor and media interest in recent months with major diamond finds at Cullinan mine which sold at record prices. The “Blue Moon” became the world’s most expensive diamond, fetching $48.5 million at a Sotheby’s auction in November.

More recently, Petra sold a massive 121-carat white diamond from the same mine for $6 million.

The company ignored the market weakness and embarked on a project to extend the life of Cullinan. The new pit at Cullinan, located northeast of Pretoria, is due to come on stream before the end of 2016, Mining.com reported.

“While the rough diamond market appears to be making a cautious recovery as compared to last year, the polished diamond trade continues to find it tough going,” the Antwerp World Diamond Centre said in a statement. “The significant monthly fluctuations demonstrate that it is too early to draw far-reaching conclusions.”

The Antwerp World Diamond Centre is a private foundation that promotes Antwerp as the global capital of the diamond industry.

Lack of firm evidence for a diamond market recovery is not deterring diamond exploration.

A Namibian joint-venture with De Beers, Debmarine Namibia recently took possession of its sixth mining and exploration vessel — the $160 million SS Nujoma. The 113-meter SS Nujoma is the most sophisticated diamond sampling and exploration vessel in the world, according to RMB Namibia, which helped finance it, Business Day Live reported.

The joint venture has five other vessels. They operate in the world’s largest known diamond deposit off the southern Namibian coast.