The main news from the Diamond Trading Company (DTC) sight this week in London is another rise of 4-22% for small rough diamonds, with the sight's total sales estimated to comprise some $600 million, the Israel Diamond Exchange website reports.

The rise in prices is the result of increased demand in the rough market, which causer traders in secondary markets to pay high premiums for DTC diamonds. In the January sight, the DTC preferred not to raise prices, but rather to adopt a policy of stability.

IDEX reports that prior to this month's sight, a number of deal had already been closed between sightholders and traders in which sightholders sold many parcels of rough diamonds at high premiums, which points to a high demand and an existing lack of rough product in the market.

Now, according to IDEX, traders can expect to pay a double premium – the premium they've agreed to pay the sightholders, and the DTC's higher prices.

DTC spokeswoman Louise Prior said in response that the DTC "has indeed raised prices by a mid-to-high single-digit percentage for most rough parcels. The rise in prices reflects the data we are receiving from various officials in the market about price levels."