Rough diamonds show resilience

His assessment is based on continued reports of strong demand from diamond producers, and the way the market is coping with the burgeoning supply from the Marange diamond field in Zimabwe. Kilalea said the impact of Marange on rough supply is a major unknown factor.

He said: "Increasingly, it appears as if production from the alluvial deposits will be much higher than many had forecast, with estimates ranging between $500m and $1bn on an annual basis. "How long the weathered portion of the conglomerate deposit lasts is also unclear, but what does appear more certain is that the Marange goods are not having a dampening impact on the market right now despite the growing supply from the mines.