Lucapa Diamond’s whopping 163-carat stone — hailed as “the world’s most beautiful” — has fetched $US33.7 million ($44.4 million) at a Swiss auction.

The emerald-cut diamond is the biggest gem cut from a record 404-carat stone discovered at the company’s eastern Angola diamond mine, Lulo, in February 2016.

It is reportedly the biggest diamond found in the country and the 27th biggest ever recorded.

The 163-carat diamond took 11 months to cut and polish and is featured in a necklace designed by Swiss high end jeweller, de Grisogono (pictured above).

The buyer has not yet been identified, according to reports.

Meanwhile Lucapa (ASX:LOM) says it’s on track to break its record 2017 annual production target from Lulo.

A selection of Lulo “specials” from October. Pic: Lucapa Diamond Co.

This is on the back of a monthly treatment record of 29,657 bulk cubic metres (bcm) of alluvial gravels from Lulo — 40 per cent owned by Lucapa — in October.

So far, 217,999 bcm has been treated year-to-date, which already exceeds last year’s total of 189,333 bcm.

Lucapa — as well as its Lulo JV partners — is on track to beat its targeted treatment rate of 240,000 bcm for 2017.

Diamond production for October came in at 2905 carats, up 22.3 per cent month-on-month, bringing year-to-date carats recovered to 16,484 carats.

A total of 49 “specials” — diamonds weighing more than 10.8 carats — were recovered last month, the second highest number produced in a month at Lulo.

Lucapa's share price over the past year. Source:
Lucapa’s share price over the past year. Source:

So far in November, “Type IIa” diamonds weighing in at a hefty 129.5 carat and 78.6 carat have been recovered at Lulo.

Type lla are regarded as the most valued and purest type of diamonds. Carat weight is one of the major factors affecting the price of a diamond, along with cut, clarity and colour.

Lucapa also owns a 70 per cent stake in Mothae kimberlite project in Lesotho which it expects to bring into production in second half of 2018.

The stock (ASX:LOM) was trading 2 per cent higher at 27c in afternoon trade AEDT.