In November 2003, miners at Letseng discovered a 216-carat flawless diamond which fetched $2.31 million, equivalent to $10,750 per carat.
A year later, a spectacular 123-carat flawless white diamond was discovered and sold for $2.33 million.
In January 2005, Letseng produced four more flawless stones in just six days that together weighed 366 carats. A flawless 76-carat stone was recovered, followed two days later by a 112-carat stone. Then a 106-carat beauty turned up and a further 72-carat stone was recovered.
A 215-carat flawless diamond was also discovered in January 2007 and sold for $8.3 million.
Most recently a 494-carat white diamond was recovered from the Letseng diamond mine. This fabulous stone, now named the Letseng Legacy, is the eighteenth largest diamond ever found.
The newly discovered diamond is currently insured for $15 million until its true value can be determined. The Letseng Legacy will be sold on tender in Antwerp on November 14.
Letseng, however, is most famous for the rock found in 2006.
A 603-carat diamond named the Lesotho Promise was recovered from Letseng in August 2006. This sparkly beast is currently the fifteenth largest rough diamond ever found. The Lesotho Promise was rated a class D stone, meaning it has no color blemishes. This means that it is of the clearest quality.
The Lesotho Promise sold in October 2006 for a cool $12.4 million.
The Lesotho Promise is the largest diamond found at Letseng since the early 1960s. A 601-carat stone named the Lesotho Brown was discovered in 1961.
The Letseng Mine has produced four diamonds weighing over 500 carats and numerous stones over 100 carats in weight since the existence of diamonds has been known in the area. It is truly one of the richest diamond mines in the world.
In fact, the average value per carat of production from the Letseng Mine is nearly 20 times the industry production average, which reflects the larger size and higher quality of the stones recovered. The mine also has the highest percentage of large diamonds (over 10 carats) of any known kimberlite mine, while having relatively low carat weight per ton of ore production.
The Letseng Mine includes production from two kimberlites that are estimated to contain $4.7 billion in recoverable resources.
The first diamonds were discovered in the financially destitute mountain kingdom in 1957, and a modest mining industry was established in the 1960s. During the 1960s and 1970s, several large gems were recovered from Lesotho's mines and the industry employed thousands of people.
During the 1980s, mining activity in Lesotho's Maluti Mountains ceased because of low world market prices for diamonds and royalty disagreements between the government and mining companies.
London-based Gem Diamonds Ltd currently operates this exceptionally productive diamond mine and has 70% ownership, with the Kingdom of Lesotho owning the remaining 30%.
While Letseng certainly makes the headlines with its large diamond discoveries, the mine will never produce anything as big as BPM 37093.
BPM 37093 is the mother of all diamonds. It weighs a staggering 10 billion trillion trillion carats!
For those of you counting, that's a one followed by 34 zeros.

I'm not pulling your leg.
BPM 37093 is at the heart of a burned-out star. And the carbon core of BMP 37093, scientists figure, has solidified into a giant diamond because of the unimaginable amount of pressure from the collapsed star. BPM 37093 has been nicknamed Lucy after The Beatles' hit, Lucy in the Sky with Diamonds.
The diameter of this monstrosity is estimated to be 2,500 miles, larger than the Earth's moon. It's been estimated that you would need a jeweler's loupe the size of the sun to grade this diamond.
Unfortunately for treasure hunters, BPM 37093 is about 50 light-years from Earth, in the constellation Centaurus. That's about 294 trillion miles away. In other words, traveling at 1,000 miles an hour, it would take over 33.5 million years to get there.
Back on Earth, the largest cut diamond today is the 530-carat Star of Africa. This stone is part of the Crown Jewels of England. It was cut from a 3,100-carat gem, the biggest ever found.