Gem Diamonds hit a record quarterly average per-carat price in the fourth quarter of 2010 - $3,291 p/c compared to $1,680 in Q3, the company reports.

The diamond company's Ellendale mine in Australia, a major yellow diamond supplier that last year negotiated a 25% price hike with Tiffany&Co, also saw record quarterly average prices, with stones from the mine selling for an average $3,482 p/c compared to $2,792 p/c in Q3.

In Q4 2010, Gem Diamonds also sold three white diamonds described as "exceptional" – with weights of 196, 184, and 116 carats for a total of $28.5 million and an average per-carat price of $57,427.

An additional 48 diamonds sold during the quarter reported fetched over $20,000 p/c, including a 4.68-carat blue rough diamond that brought in $155,000 per carat, a record for diamonds from the Letseng mine in Lesotho.

CEO Clifford Elphick said that reports of strong diamond jewelry sales in the important US Christmas season; growing sales of diamond jewelry in Asia; and the fundamental supply-demand imbalance has meant strongly rising prices for rough diamonds and to a lesser extent polished diamonds.