The 10 biggest diamonds in the world

“Sergio”, a black carbonado diamond from Brazil discovered in 1893, beats all its rivals for weight. These so-called black diamonds are rare and scientists are still in debate over their origins. There are some that believe these black diamonds come from outer space, having travelled to Earth as fragments of an ancient meteor. Sergio (Portuguese Carbonado do Sergio) is the largest carbonado and the largest rough diamond ever found. It weighs 3167 carats and was found in the State of Bahia in Brazil in 1895. Like other carbonados it is believed to be of meteoritic origin.

2. Cullinan Diamond

The Cullinan diamond is the largest non-carbonado and largest gem-quality diamond ever found, at 3106.75 carat (621.35 g, 1.37 lb) rough weight. About 10.5 cm (4.1 inches) long in its largest dimension, it was found on 26 January 1905, in the Premier No. 2 mine, near Pretoria, South Africa., and was named after the owner of the mine, Sir Thomas Cullinan. It was given as a gift to the King of the United Kingdom (Edward VII) and was taken to Amsterdam to be cut. Nine large stones and 96 stones were taken from the rough diamond, including the famous Star of Africa (Cullinan I) which is 530.2 carats and is now part of the Crown Jewels, inserted into the Sceptre with the Cross. The value of the Cullinan diamond has been estimated at $2 billion.

3. Excelsior Diamond

Found in 1893 in South Africa, this huge rock was cut into many smaller pieces. The largest gemstone cut from this famous diamond was only 69.68 carats, but many in the diamond industry believe that much larger diamonds could have been taken from the original stone. Intriguingly, another diamond of a similar weight (around 1,000 carats) could have been included in this list, but little is known about it: It’s a rare black diamond that has been called The Nameless. No-one seems to know where it came from or when it was discovered, so – for now – it remains a side-note. 

4. Star of Siera Leone

Star of Sierra Leone diamond was discovered by miners on February 14, 1972 in the Diminco alluvial mines in the Koidu area of Sierra Leone. It ranks as the third-largest gem-quality diamond and the largest alluvial diamond ever discovered.  This diamond has 968.9 carat (193.78 g)

On October 3, 1972, Sierra Leone's then-President, Siaka Stevens, announced that Harry Winston, the New York City jeweller, had purchased the Star of Sierra Leone for under $2.5 million.^[2]  The stone was initially cut into an emerald shaped stone weighing 143.2 carats (28.64 g) but was later re-cut due to an internal flaw,^[3] eventually resulting in 17 separate finished diamonds, of which 13 were deemed to be flawless. The largest single finished gem was a flawless pear-shaped diamond of 53.96 carats (10.792 g). Six of the diamonds cut from the original rough were later set by Harry Winston into the "Star of Sierra Leone" brooch.^[4] A rare characteristic of the stone is its perfect chemical purity: it is ranked as a type IIa diamond, a category which includes less than 1% of all diamonds.

5. Incomparable Diamond

At 890 carats (just over 6 oz) this Congolese rough diamond was discovered by a young girl in 1989. The smart child noticed the diamond in a pile of rubble and passed it on to her uncle, who sold it to diamond dealers. Like many of the world’s diamonds, it ended up at one point in the Belgian city of Antwerp, famous for its diamond district. It took experts years to cut the rough diamond into smaller gems, but they managed to create a beautiful yellow-brown stone weighing 407.48 carats that had been cut into an unusual triangular shape. Strangely enough, this fantastic gemstone actually appeared on eBay in 2002, but went unsold. 

6. The Woyie River Diamond

The Woyie River Diamond was recovered on 6 January 1945 from the Woyie River near Koidu in eastern Sierra Leone.^[1] The uncut stone weighed 770 carats (154 g),^[2] and at that time it was the largest alluvial diamond ever found, and the third largest diamond discovered in Africa, after the Cullinan Diamond and the Excelsior Diamond. The alluvial Star of Sierra Leone, discovered at the Diminco mine in Sierra Leone in 1970, is larger at 968.9 carats (193.78 g) uncut. 

The uncut Woyie River Diamond had a broadly lozenge shape, measuring 71 × 53 × 32 millimetres (2.8 × 2.1 × 1.3 in), with one unusually flat cleavage plane. The rough diamond was brought to London, where it was viewed by Queen Mary in October 1947 and then exhibited at the British Industries Fair in May 1949. The stone was cut by diamond cutters Briefel and Lemer in London (who also cut the Williamson pink diamond) into 30 gems weighing 282.36 carats (56.472 g) in total, including 10 of over 20 carats (4.0 g) each. The largest of the gems is the Victory Diamond which is weighs 31.35 carats (6.270 g) and is Emerald cut (occasionally described as "step cut").

7. Golden Jubilee Diamond

The Golden Jubilee Diamond is the largest cut and faceted diamond in the world. It weighs 545.67 carats (109.13 g). It outweighs the Cullinan I by 15.37 carats (3.07 g). The Golden Jubilee Diamond was discovered in the Premier Mine, which is also the origin of the Cullinan diamond (1905) and other notables such as the Taylor-Burton (1966) and the Centenary (1986). The Cullinan I, also known as the Great Star of Africa, had held the title of the largest cut and faceted diamond since 1908. The diamond is valued at 4–12 million US dollars.

The Golden Jubilee Diamond was cut from a large brown diamond of 755.5 carats (151 g), found in the prolific blue ground of the Premier Mine in South Africa in 1985. First known as the "Unnamed Brown," the Golden Jubilee was given to Gabriel Tolkowsky by De Beers for the purpose of testing special tools and cutting methods that had been developed for use on the colourless D-colour Centenary. Because of its deep cracks and several inclusions, the Golden Julilee Diamond was cut in a specially designed underground room free from vibrations. The yellow-brown diamond was transformed through a fire rose cushion cut. Until 1990, the diamond remained largely unknown to the outside world, requiring two years to bring it to its current state. The unnamed diamond was brought to Thailand by the Thai Diamond Manufacturers Association to be exhibited in the Thai Board of Investment Exhibition in Laem Chabang and was selected to herald De Beer's centennial celebrations in 1988. The Golden Jubilee was purchased from De Beers by a group led by Henry Ho of Thailand in 1995.

9. The Vargas Diamond

The Vargas Diamond, discovered in Brazil on August 13, 1938 by Joaquim Venancio Tiago and Manoel Miguel Domingues, was 726.6 carats (145.32 g) when pulled out of the ground. Twenty-nine smaller diamonds were carved from the larger rough Vargas Diamond including the 48.26-carat (9.652 g) 
This one was named for Getúlio Dornelles Vargas, who was the President of Brazil at the time. The diamond eventually found its way to Amsterdam and was finally bought by someone not only famous in jewelry circles, but who has also become synonymous with the industry as a whole: American jeweler, Harry Winston. Twenty-nine smaller stones were cut from this rock, with the largest being a flawless 44.17 carat gem which had been re-cut by Winston himself. The Vargas has 726.6 carats.

The Jonker Diamond

This giant gem, found in South Africa in 1934, was found by a settler called Johannes Jacobus Jonker, hence its unusual moniker. It’s believed the rough diamond was eventually cut into 13 smaller gemstones, with the largest diamond, the Jonker I, still weighing in at an incredible 142.9 carats. Diamonds are valued by weight, color, clarity and various other factors. However, with a colorless flawless diamond valued at $26,125 per carat, the Jonker I could be worth as much as $3.7 million!