The 3 largest Gem Quality Diamonds ever discovered

April 16 2021

Learn all about the top 3 largest Diamonds ever discovered, where they were found, and where they are now!

Over the years there have been many notable Diamond discoveries, bringing us some of the largest Diamonds ever discovered. Before they are cut and polished into the beautiful Diamonds we see today, they are originally found in their natural state; this is when they are called ‘Rough cut’ Diamonds.

These Rough cut Diamonds are then assessed on how best to cut and polish the stone, including what shapes and carat weights are to be formed.
When we talk about a Diamonds carat weight in Jewellery, this weight is the final cut weight of that stone. However, when the stone was originally found, it is weighed and measured, and that weight is called the original 'Rough cut' weight.

As well as the cutting methods, Diamonds are also assessed on the stones qualities. This is because not all Diamonds that are mined are of a ‘gem-quality’. A Diamond of Gem-quality, simply means it fits within the Gemological Gradings for the 4 C’s.
Find out more about the 4 C’s here: Diamond Gradings.

Below we’ve listed the 3 largest Rough-cut, Gem-Quality Diamonds ever mined!

1. Cullinan Diamond

The Cullinan Diamond is the largest gem-quality Diamond ever found, weighing in at an enormous 3,106.75 carats. A miner named Thomas Powell discovered the Diamond in the Premier Mine in Cullinan, South Africa. The Diamond was named after Sir Thomas Cullinan, the owner of the Diamond mine. It was later suggested that the Diamond was probably part of a much larger octahedral crystal.

The Diamond was gifted to King Edward VII as a token of the loyalty and attachment of the people of Transvaal to his throne.

It was presented to him on his birthday, and he declared that he would ensure ‘the Diamond was to be kept and preserved among the historic Jewels of the heirloom of the Crown’.  
The Diamond was cut by the Asscher brothers into nine large stones and a number of smaller stones.

The most known Diamond is the famous ‘Great Star of Africa’, weighing 530.2 carats and cut into a Pendeloque shape. It is still the largest clear cut diamond in the world, and sits at the top of the Sovereign’s Sceptre with Cross.

The second largest, known as the Second star of Africa, is a cushion-cut Diamond, and is set in the front of the Imperial State Crown.

The other 7 larger stones from the Cullinan are set into brooches, pendants and even rings; all owned by the Royal family.

2. Lesedi La Rona

Found in the Karowe mine in Botswana, the Lesedi La Rona is the 3rd largest Diamond ever to have been discovered, and the second largest of Gem Quality. It was mined fairly recently on the 16th November 2015.
As a Rough cut Diamond, it weighs in at 1,111 carats, and is the largest Diamond to have ever been recovered using automated Diamond machines. With an estimated age to be over 2.5 billion years old, it has been suggested that the Diamond could be sold for $40-60 million.
The exact value of this Diamond cannot be determined until it has been decided on how to be cut, and more details about its grades are known.

Going to public auction in June of last year, the Diamonds bidding fell short of the reserve, and was  kept by founder Lucara Diamond. However, on Tuesday 26th September Graff Diamonds (a multinational London based Diamond Jeweller) announced they'd purchased the Diamond for $53 million!

3. Excelsior Diamond

Back in 1983, at the Jagersfontein Diamond Mine in the Orange Free stage, a worker was loading gravel into a truck. It was in a shovelful of gravel that he noticed the Diamond, and reported it directly to his mine manager.

The rough Diamond measured 971 carats and was categorized as G in colour, with a number of black inclusions (common from Diamonds in that mine). The Diamonds discovery was largely unacknowledged, and it is believed to be due to the contract between the mine and the London firm which purchased the Diamonds having had expired that very day. It was shipped to London and eventually sold for £16,250, roughly 1.5-2 million today.

The rough Diamond was cut into 11 different stones, ranging from 9-69 carats in weight, in a mixture of pear and marquise shapes.
Nowadays, the Diamonds are owned by various people, and have been used in many fine Jewellery creations.

Finally, when it comes to talking about the largest Rough-cut Diamond EVER discovered, regardless of being Gem-Quality or not, the Sergio Diamond holds the crown!

Sergio

Even bigger than the famous Cullinan Diamond, in 1985 in the State of Bahia in Brazil, the largest rough Diamond ever found was discovered. Weighing 3,167 carats, (around 60 carats bigger than the Cullinan), this Carbonado black diamond was recovered. These types of Diamonds are not of gem quality, and are much more porous than other Diamonds. Not holding the typical aesthetics of a Gem Diamond, Carbonado Diamonds are black or dark grey, and are typically aggregates of tiny black crystals. Some geoscientists believe the Carbonados are of an extraterrestrial origin!

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