The famous Golconda diamonds, known for their clarity and brilliance, may originate from a volcanic mine located 300 km from where they were extracted.
Researchers may have discovered the true origin of the renowned Golconda diamonds, such as the Hope and Koh-i-noor, Live Science reported on April 21.
The Hope Diamond – one of the most famous gemstones in the world. (Photo: Telegraph).
Golconda diamonds are special due to their extremely low impurities and nitrogen content, making them exceptionally clear and free from inclusions that diminish their sparkle. They are also quite large. The Koh-i-noor diamond, currently part of the British Crown Jewels held at the Tower of London, weighs 105.60 carats. The Hope Diamond, displayed at the Smithsonian National Museum of Natural History in Washington, D.C., weighs 45.52 carats.
These Golconda diamonds were discovered in southern India from the 1600s to the 1800s. They were mined from alluvial deposits – shallow pits dug into river sediments. However, before this, the diamonds were brought to the Earth’s surface in large volcanic rock formations known as kimberlite, and experts were unaware of the origin of the kimberlite that contained these diamonds.
A new study published in the journal Earth System Science suggests that the Golconda diamonds may originate from the Wajrakarur kimberlite mine in Andhra Pradesh, India, located about 300 km from where they were mined.
To trace the origin of the Golconda diamonds, geologists Hero Kalra, Ashish Dongre, and Swapnil Vyas from Savitribai Phule Pune University examined the chemical properties of the surrounding kimberlite and lamproite rocks. These types of rocks form from the Earth’s crust and upper mantle, where most diamonds are formed.
The research team found that the kimberlite from the Wajrakarur mine could have been pushed up from the depths where diamonds form and contains minerals that commonly occur with diamonds. They then conducted surveys using remote sensing data, such as satellite images, vegetation measurements, and moisture levels. The surveys revealed that an ancient river, long dried up, may have transported diamonds from Wajrakarur to the Krishna River and its tributaries, where the diamonds were found.
However, these results are not definitively accurate, according to Yakov Weiss, a geochemist studying diamonds at the Hebrew University of Jerusalem. In the new study, the authors analyzed the geochemical characteristics of common diamonds from the lithosphere – the Earth’s hard crust and upper mantle – and determined that the Wajrakarur mine may contain diamonds. However, Golconda diamonds formed at greater depths in the mantle, possibly in the transition zone near the Earth’s core.
It is very difficult to directly detect the origin of Golconda diamonds because they lack impurities containing fluids from the mantle – where they began to form. Weiss noted that this makes them aesthetically pleasing and desirable, but provides little information for geochemists. Therefore, the origins of Golconda diamonds may always remain a mystery.
