Gemfields’ latest mixed-quality rough ruby auction raised $52 million. That is nearly the same as its February sale, even though this auction had less than half as many carats on offer.

All the stones came from Montepuez Ruby Mining (MRM), in the Cabo Delgado province of northern Mozambique. MRM sits on one of the most significant ruby deposits found in recent decades. Gemfields owns 75% of MRM, and Mozambican company Mwiriti Limitada owns 25%. All proceeds from the auction go back to MRM in Mozambique, and the company pays royalties to the Mozambican government on the full sale price.

The auction ran Oct. 5–16. Bidders viewed the stones in person in Bangkok, then placed sealed bids online. Gemfields sold 90 of the 99 lots offered, and 46 companies placed bids.

The average price across all lots sold was $564.54 per carat, about double the February auction’s $279.39. Based on Gemfields’ published results, this is the highest average for any of its mixed-quality ruby auctions. The company itself said results aren’t always directly comparable from one auction to the next, because the size, color, and clarity of the stones on offer vary.

Adrian Banks, Gemfields’ managing director of product and sales, said the auction weighed just over 20 kilograms and comprised mostly higher-quality rubies.

“The lower volume reflects the year’s operational challenges and the Trade Select auction strategy introduced in June, under which selected grades and categories are now offered separately,” he said in a statement.

Gemfields’ operational challenges in Mozambique

Heavy rain in the first quarter, along with problems commissioning a new processing plant, kept MRM from mining the most favorable areas of its concession, Gemfields said in June. In the same statement, the company reported attacks this spring on villages 15 to 35 kilometers from the mine.

The operation also is hampered by illegal mining. More than 1,000 people enter the concession each day, according to MRM.

The auction comes as Mozambique tightens its mining rules. A law signed in June requires the state, through a new National Mining Company, to hold a free stake of at least 15% in mining projects. On Oct. 20, President Daniel Chapo said that stake would be 20%. The government has not said whether the rules apply to existing operations such as Montepuez. Gemfields did not respond by press time to a question about whether they could affect the mine.

Top: Rough rubies from Gemfields (photo courtesy of Gemfields)