Type IIa

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The Letseng mine in the small Kingdom of Lesotho, South Africa has just uncovered another massive diamond rough: a 198-carat stone, roughly the size of a large letseng 198 caratstrawberry.

A diamond over 100 carats is rare enough – with only about 10 to 15 found each year worldwide – but a rough that is nearly 200 carats is an exceedingly rare find. A stone of this size is expected to yield a polished diamond around 100 carats, or half the weight of the rough it originated from.

Even though the stone’s size is impressive, it is not even close to being the largest ever uncovered from the Letseng mine. In fact, the Letseng mine is well-known for churning out large, quality rough over the years, and has the highest price per carat production of all the mines in the world. Some of the largest include the Letseng mineLesotho Promise, the 15th largest diamond in the world at 603 carats; the Letseng Legacy at 493 carats, and the Leseli La Letseng at 478 carats which are 18th and 20th largest respectively.

What makes this rough even more valuable is its’ designation of Type IIa, which constitutes less than 2% of all natural diamonds. Type IIa diamonds have no measurable nitrogen impurities, making them chemically pure. This not only gives them exceptional optical transparency, but also a high likelihood of achieving a colorless (D-E-F) grade and a high clarity grade. Officials from Gem Diamonds Ltd, which own the majority stake in the Letseng mine, confirmed this after inspection of the stone noting it as “an exceptional white, high-quality diamond that displays no fluorescence”.

Martin Potts, a London-based mining analyst has estimated the 198 carat stone to fetch somewhere between $12 to $15 million.

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DiamondThe most flawless, biggest briolette ever to surface at auction weighing at a stunning 75.36ct broke records! This diamond was sold for a world record at $11,145,734 from an anonymous buyer at Christie’s Hong Kong’s Magnificent Jewels sale. This pendant necklace was originally valued at a pre-sale low estimate of $8.5 million, which it easily surpassed.  It did fall short of its high pre-sale estimate of $12.5 million.

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The briolette is a traditional cut popular in the Victorian times but has recently become more popular in precious and semi-precious stones. It is a stone cut into a three-dimensional waterdrop shape.  Its elegant pear shape with cut facets dangles below a marquise-cut purplish-pink diamond. Adorned with stations of smaller briolettes with 18 karat white and rose gold adjustable neck chain, this piece is a classy stunner!

An auction spokesperson said the diamond was “perfect,” and had the proof of an assessment with the Gemological Institute of America. The GIA rated the stone Type IIa, which is the top quality grade.  The diamond is similar to the British Queen Elizabeth’s one she has set in her crown. Christie’s jewellery specialist, Chiang Shui-Fung, says the diamond is extremely rare.

The briolette is special because they have to find a piece rough and big enough to cut into that style. The diamond came to an American dealership named William Goldberg, as a 160.5- carat rough weight and had to be shaped into the now 75.51 carat diamond. To achieve this brilliant rare cut William Goldberg had to sacrifice more than half the stone’s weight in the meticulous cutting process. The diamond is now a stunning piece and will be remembered as a historical record breaking event.

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Diamond“No country but India produces diamonds. Those which are brought to our part of the world are only the refuse, as it were, of the finer and larger stones. For the flower of the diamonds are all carried to the Great Khan and other kings and princes of the region. In truth they possess all the treasures of the world.”

Marco Polo

Although Marco Polo lived in a time before mines in Canada, Russia, South Africa, Australia were discovered, diamonds discovered in his era are some of the most famous in the world.

Many of these most famous diamonds hail from the Golkonda (alternative spelling: Golconda) region which was the capital of the ancient Kingdom of Golkonda in south India, ruling from 1518 – 1687 AD. The Kingdom towered above an expansive granite wall approximately 120 meters high on all sides, with additional granite structures surrounding it. It was aptly named the Golconda Fort, wherein it housed the most powerful Muslim sultanates of the region and also a flourishing diamond trade center – the first of its kind.

The Golconda mines, aside from producing stones of astonishing size, also lend these diamonds a quality that goes beyond the 4 C’s. Diamonds of proven Golconda provenance are a specific type of rare diamond classified as Type IIa. This classification is assigned to approximately 1% of all diamonds, and denotes the highest carbon purity, with either miniscule or no amounts of nitrogen in the crystal lattice structure. Nitrogen is the elemental impurity which imparts a yellowish hue in diamonds, so the lack of nitrogen makes for a pure colorless (D, E, F) color diamond. However it is not a mutually exclusive relationship; just as not all colorless diamonds are Type IIa, not all Type IIa diamonds are of Golcondan origin. Nowadays though, it is common for people in the industry to refer to any Type IIa diamonds as “Golconda material”.

Perhaps due to this highly pure carbon composition, they also exhibit a superior degree of transparency. Despite being the most defining quality of diamonds of this origin, it has been notoriously difficult to describe in words. Jean-Baptiste Tavernier, a 17th century French explorer, described these gems to be “pools of crystal water”. This trait gives the diamond a softer, pure look, as the light just seems to pass right through it as if it were invisible.

In addition to this, they also exhibit a soft blue glow when exposed to natural sunlight. Golconda stones are the true blue white diamonds of legend. This is not to be confused with blue ultraviolet fluorescence, prevalent in over 30% of diamonds, which causes the diamond to reflect a blue color under dark UV lighting.

To summarize, Golcondan diamonds can be identified through these three characteristics: an ultra-white appearance, high degree of limpidity in the crystal, and a slight blue glow in direct sunlight.

Some of the famed diamonds excavated from the mines include the Darya-i-Noor and the Noor-ol-Ain, two pale pink diamonds of approx. 185 carats and 60 carats respectively, which both reside in the Iranian crown jewels. Another fancy colored Golcondan diamond, perhaps the most-well known jewel of all, is the Hope Diamond, a 45.52ct fancy dark grayish blue that is displayed in the Smithsonian Museum of Natural History. Other diamonds with the same lineage include the Wittlesbach, the Regent, and the Koh-i-Noor.

True Golcondan diamonds, if not housed in the finest museums or part of a country’s imperial crown jewels, demand a significant premium on the secondary market. The Archduke Joseph diamond, a 76.45 carat colorless, flawless diamond of Golcondan origin, was sold recently for a record price of $21 million.

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