“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.