The Hope and Koh-i-noor: New insights into the world’s most famous diamonds

May 5, 2024

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The Hope and Koh-i-noor: New insights into the world’s most famous diamonds

Could the famous Hope Diamond and Koh-i-noor have originated from a volcanic outcrop nearly 300 kilometres from where they were discovered in southern India?

Known as Golconda diamonds – mined in the Godavari-Krishna delta region of Andhra Pradesh – these stones were unearthed between the 1600s and 1800s.

The Golconda diamonds also include the Orloff, Great Mogul, Nizam, and Pitt. This collection is well-known for its rare colours and large-carat sizes. Because of the paucity of nitrogen atoms, the majority of them have been classified as Type IIa diamonds.

However, according to new research published in the Journal of Earth System Science, the diamonds are more likely to originate from the Wajrakarur kimberlite field, around 300 kilometres from where they were located and mined.

The Hope and Koh-i-noor, which are both surrounded by controversy from colonial times, were found in so-called placer mines, which are shallow pits dug into riverside sediment.

Diamonds come to the Earth’s surface by large volcanic eruptions called kimberlites. To date, no one has discovered where the kimberlite rocks that bore these diamonds is located.

Three geoscientists at India’s Savitribai Phule Pune University – Hero Kalra, Ashish Dongre and Swapnil Vyas – have attempted to trace the source of the Golconda diamonds by studying the chemical signatures of nearby kimberlites and lamproites. Now, they may have the answer.

The scientists believe that kimberlite rocks from the Wajrakarur field likely rose from the depths of the Earth, where diamonds are forged and host minerals that tend to co-occur with diamonds. They conducted surveys using remote-sensing data, such as satellite imagery and vegetation and moisture measurements.

According to Yaakov Weiss, a geochemist who studies diamonds at The Hebrew University of Jerusalem, the findings are not conclusive.

He notes that the researchers studied the geochemistry of common diamonds from the lithosphere — the rigid crust and upper mantle — and determined that the Wajrakarur field could host diamonds.

The Golconda diamonds, however, formed deeper in the mantle, perhaps as deep as the transition zone near Earth’s core.

Wiess was not involved in the study but told Live Science that there is still a deal of uncertainty surrounding the origins of these diamonds.

“The analysis is related mainly to lithospheric diamonds, and we believe the larger diamonds are coming from deeper in the Earth,” he explained.

Scott Sucher, a world-renowned stone cutter, has closely followed this research. He has intimate knowledge of the Hope and Koh-i-noor diamonds, as well as other famous stones, and has cut perfect replicas.

His collection comprises 38 exacting replicas of the world’s most famous diamonds.

The US Discovery Channel contacted Sucher for assistance on a 14-month project entitled Unsolved History: the Hope Diamond, which first aired in February 2005.

The program gave Sucher the opportunity to handle the unset Hope diamond, the 31-carat Blue Heart diamond and Napoleon’s necklace – a 234-diamond necklace that Napoleon gave to his second wife, Marie-Louise.

Sucher then worked with the Natural History Museum in London to recreate a replica of the historic Koh-i-noor. The process took 12 months – photo analysis took four months alone – and concluded in July 2007.

Watch: Secrets of the Hope Diamond

He told Jeweller, “Recent studies have concentrated on the formation of deep mantle diamonds and to find the possible origin of Indian diamonds would be significant.

“Imagine the chemistry necessary to produce these diamonds, especially the latter, a flawless pink diamond of 400 carats and compare it to the modern-day pinks that came from Argyle.”

With degrees in Chemistry and Semiconductor Manufacturing – the former is important in understanding colour and the latter in crystal formation – Sucher says, “There’s a lot of information on the Internet regarding famous diamonds. Unfortunately, a lot of it isn’t true.

“However, if history is correct that these are all Golconda stones, to be transported 300 kilometres makes one wonder what else may remain in the ancient river channel.

“The findings are tantalising and suggest that much more needs to be done to understand if large diamonds originated from the deep mantle.”

The Koh-i-Noor is one of the largest cut diamonds, weighing 105.6 carats. It is part of the Crown Jewels of the United Kingdom and is currently set in the Crown of Queen Elizabeth.

The Hope Diamond is a 45.52-carat fancy colour blue diamond. It was previously known as the French Blue.

Over the past 400 years, the diamond has been owned by many influential figures. In 1958, US jeweller Harry Winston donated it to the Smithsonian Institution’s National Museum of Natural History.