The Letšeng mine in Lesotho produces the highest quality gem diamonds, consistently achieving the highest price per carat of any kimberlite mine in the world. It is also famous for its large top colour white diamonds, and has produced four of the 20 largest white diamonds ever recorded since Gem Diamonds took the mine over in 2006.
Famous Letšeng Diamonds
The Lesotho Legend
Sold for: US$40 million
In January 2018, one of the largest diamonds in history was discovered at the Letšeng mining operation at an elevation of 3 100 metres above sea level in the Maluti mountains of Lesotho in Southern Africa.
Weighing 910 carats, this exceptional top-quality D colour, Type IIa rough diamond is the fifth largest gem quality diamond ever found and the largest diamond to be recovered at Letšeng.
This magnificent and historically significant diamond has been named the Lesotho Legend to celebrate not only the mine, but also its country of origin.
The 603 carat 'Lesotho Promise'
Sold for: US$12.4 million
The 603 carat Lesotho Promise was recovered in August 2006 and is ranked in the top 20 of the world’s largest white diamonds on record. The Lesotho Promise was sold for US$12.4 million in October 2006 and was
subsequently polished into 26 D flawless and internally
flawless diamonds, the largest of which was a 76 carat pear shaped
All 26 polished diamonds were fashioned into a single necklace by Graff.
The 550 carat 'Letšeng Star'
Sold for: undisclosed*
The 550 carat Letšeng Star was recovered in August 2011 and was so named to signify the growing number of ‘stars’ in Letšeng’s
constellation of large diamonds recovered. The Letšeng Star is also ranked in the top 20 largest white rough diamonds on record. This diamond yielded 12 pairs of pear shaped diamonds, as well as a
main polished stone of 33 carats, also a pear shape, to form a unique collection of over 165 carats of D flawless and
internally flawless polished gems stemming from this single rough diamond.
The 493 carat 'Letšeng Legacy'
Sold for: US$10.4 million
The 493 carat white diamond was named the Letšeng Legacy to highlight the growing legacy that the Letšeng mine in Lesotho was creating as a producer of significant large white
diamonds. This diamond was recovered in September 2007 and was sold for US$10.4 million in November 2007. Twenty polished diamonds were extracted from this rough diamond.
The 478ct Leseli La Letšeng (Light of Letšeng)
The 'Leseli La Letšeng', which translates to ‘Light of Letšeng’, reflecting the
diamond’s remarkable colour and clarity, was recovered in September 2008. This diamond was the third significant recovery from the Letšeng mine in as many
years and was sold in November 2008 for US$18.4 million (during the height of the global financial crisis).
The fame of this diamond extends further in that it revealed a 102 carat round shaped, D colour internally flawless diamond, making it the largest round-shaped polished diamond ever to be graded D colour internally flawless by the Geomological Institute of America (GIA). A total of 10 exquisite polished diamonds were also revealed.
The 357 carat 'Letšeng Dynasty'
Sold for: US$19.3 million
The Letšeng Dynasty was recovered in July 2015 and sold for US$19.3 million in September 2015. The name given was to symbolise the succession of diamonds from the same family.
During 2016, Graff unveiled the Venus, a 118 carat heart-shaped, D flawless diamond, which was polished from the Letšeng Dynasty, making it the largest of its
kind in the world. In total, 23 polished diamonds were extracted from this one rough diamond.
THE 314 CARAT LETŠENG DESTINY
Sold for: undisclosed*
The Letšeng Destiny was recovered in May 2015 and sold into a partnership arrangement in June 2015. The
name was given to signify a hidden power believed to control future events. During 2016, the Letšeng Destiny has yielded a main
polished 105 carat pear-shaped D colour flawless diamond, the Graff Vendôme, making it the largest cut and polished diamond of its kind in Graff’s history. Twelve smaller diamonds of D colour were also extracted from the rough diamond, totalling a polished weight of 164 carats.
299 carat yellow diamond
Sold for: undisclosed*
This diamond was recovered in December 2014 and sold into a partnership arrangement in January 2015. Unmasking its true radiance, the gem was cut and polished by
expert artisans with coloured diamond expertise, which resulted in a magnificent 132 carat fancy intense yellow cushion-shaped polished diamond, along with eight other yellow diamonds, the largest being a 21 carat fancy yellow pear shape. The 132 carat gem, aptly named The Golden Empress, was set into a breathtaking Graff signature necklace, adorned with 30 other cushion-cut yellow diamonds.
12 carat Blue diamond
Sold for: US$7.5 million
This rare 12.47 carat blue diamond was recovered at Letšeng in September 2013. It was sold a month later on tender in Antwerp for a record price of US$603 047 per carat (US$7.5 million), the highest US$ per carat for any Letšeng rough diamond sold to date.
7.87 carat Pink diamond
This exceptional 7.87 carat pink diamond was recovered at Letšeng in August 2017. It was sold in Antwerp in September 2017 for US$202 222 per carat (US$1.6 million), which is the second highest US$ per carat achieved for any Letšeng rough diamond sold to date.
Diamond types are classified by nitrogen content, namely Type I and Type II. Type I diamonds contain nitrogen while Type II diamonds are nitrogen free and are usually white or blue. Type IIa and Type IIb (blue colour) are very rare and generally thought to comprise less than 1% of all diamonds. While it is possible to obtain D Flawless diamonds from Type I diamonds, the most sought after diamonds are Type IIa Flawless diamonds. Type II diamonds have superior optical properties and have a superior overall polish to Type I diamonds.
In ancient times, incredible white diamonds were recovered in Golconda in India, and to this day Golconda diamonds have held a superior position to white diamonds produced anywhere else in the world. However, notwithstanding these Golconda gems, the Gem Diamonds Marketing Consultants and some of the world's leading Diamantaires believe that the D Flawless diamonds from Letšeng are the prize gems of them all.
Rough gem quality diamonds
These diamonds are attractive when viewed and are the easiest diamonds to manufacture and polish for jewellery.
The value of a diamond is based on rarity.
Gem quality diamonds are based on the combination of the following characteristics:
To a large degree size does matter, especially with large white D, E F & G colours. However, when dealing with rare fancy colours such as reds, blues, oranges and greens, even small stones are highly prized gems.
A range of colourless, moving to lighter yellows and browns are regarded as gem colours. The closer a diamond is to colourless, the more valuable it becomes. Deeper colours of yellow and brown, as well as rare colours such as orange, violet, purple, green, pink, blue and red are referred to as fancy colours.
Originally gem quality rough diamonds were those diamonds without cracks, twins or large inclusions, the equivalent of the polished grade SI3 or better. Lesser qualities were referred to as near-gem and included low clivage and semi-opaque rejection material.
In today's terminology, the better near-gem qualities are included as gem quality, as it is now viewed that any diamond which can provide a polishable gem be included, regardless of the fact that more splits (sawing, cleaving or lasering) are required to achieve polishable pieces.
The most desired rough gem shapes are the following:
crystals (Sharp edged octahedrons),
octahedrons with some rounding to the edges and points
rounded dodecahedral maccles
shapes that have high yielding forms either for rounds or fancy cuts
Less desirable gem shapes are cubes, irregular low yielding shapes and twinned or aggregated forms.
Other factors which influence the overall gem description would include stones with unattractive clouds, milkiness or colour banding/zoning.
Therefore, the most desired rough gem diamonds would be those having good colour, shape and internal clarity, without ignoring the size factor.
Polished gem diamonds
Based on the descriptions, a polished gem diamond requires the basic 4 C's:
Larger diamonds are rare. The size of the polished gem does matter and is further complicated by reaching stipulated price bands, such as 0.25ct, 0.50ct, 1.00ct, 3.00ct, 5.00ct, and 10.00ct and so on. The price difference between a 0.99 carat and a 1.00 carat is very high and this continues throughout all the size bands.
Diamonds come in many different colours. The colour of most diamonds range from colourless to light yellow or brown. Normal diamonds are graded on a colour scale which ranges from D (colourless) to Z (light yellow). Within this range colourless diamonds are the most rare, and the most valuable. Diamonds that are blue, pink, purple, orange, red, green or canary yellow are called "fancy colours", and are very rare.
The clarity of a polished diamond is the relative absence of inclusions or blemishes. The top clarity grade is "Flawless" and diamonds graded as such are rare. The clarity of a diamond has a direct influence on the value of a polished diamond. Therefore, the higher the clarity, the more prized and expensive the polished gem becomes.
Round Brilliant cut diamonds are more expensive than fancy shaped diamonds. This is because in the polishing process more weight is lost when polishing a Round Brilliant than when polishing a fancy shape as the latter is polished to maximise the polished weight recovered from the rough diamond.
Other important factors for polished gem diamonds
Quality of polish
It is estimated that of all the diamonds mined only 0.001% will produce D Flawless finished stones. [Bryan Boyne, G.G. (GIA)].
The quality of polish and symmetry is vital to achieve maximum brilliance, scintillation ('sparkle') and dispersion ('fire').