Ore Grade, Output and Insurgency Challenges Impact Gemfields

Declining ruby grades, illegal mining and other challenges will weigh on Gemfields’ production, quality mix and cash flow for the full year.

Ore grade for premium rubies at the Montepuez mine in Mozambique has fallen by half, the company said Monday. The number of carats of rubies per tonne dropped to 0.03 between January and May of 2026 from 0.06 in the full year of 2025.

In addition to the declining grades, the company has not been able to mine and process the most favorable areas of Montepuez due to heavy rainfall during the first quarter. It also faces a commissioning issue with its processing plant, which it expects will reduce the inventory availability for auctions for the rest of the year.  

At the end of April, rebel insurgents attacked villages within 15 to 35 kilometers of the mine, causing it to pause operations. On May 1, the miner restarted production, yet while conditions have improved and production has returned to normal levels, it is still monitoring the ongoing situation.

The company is also experiencing illegal mining, with approximately 700 individuals entering daily, which lowers the mine’s resources and recovery grades.

Gemfields held its inaugural Trade Select auction between June 22 and 29, comprising mixed-quality rough rubies and a newly introduced sapphire segment. In total, the auction garnered $23.1 million, selling 92% of its 89 lots at an average price of $66 per carat.

“We are pleased with the outcome of our inaugural Trade Select ruby auction,” said Adrian Banks, managing director of product and sales at Gemfields. “The Trade Select format was developed to sit between [Motepuez’s] traditional mixed-quality ruby auctions and the smaller mini-auctions introduced during 2025. By bringing selected grades and categories together in a focused offering, the format provides greater flexibility in matching available production with market demand, whilst also broadening customer participation.”

The miner received positive feedback regarding the auction’s format and the goods on offer, he continued. “Whilst market conditions remain challenging in certain sectors of the colored gemstone market, customer attendance was strong and bidding demonstrated continued demand across the categories offered,” Banks added.

Separately, Sean Gilbertson will step down as CEO and director of the company, taking effect July 15, Gemfields announced. Gilbertson joined the firm in 2017 and took over as CEO in March 2018. His father, mining executive Brian Gilbertson cofounded the company, initially called Pallinghurst Resources.

The miner has appointed chief financial officer David Lovett as interim CEO in conjunction with his current role.

Image: Polished rubies from the Montepuez mine. (Gemfields)