Which are the rarest diamonds in the world?

Formed deep below the Earth’s surface under incredibly high pressure and heat, the diamond is a gem that has always stood to represent elegance and wealth. Their rarity and therefore value can be determined by a number of factors, including size, clarity and colour.

Top 5 Rarest Diamonds in the World

5. Green Diamonds

Whilst green diamonds may share their colour with emeralds, the source of their colour and their chemical composition makes the two stones completely different in rarity and value. Emeralds are in the family of the beryl mineral, and their rich green colour is considered to be an ‘impurity’ of the mineral, caused by traces of chromium and, occasionally, vanadium.
In contrast, the colouring in green diamonds, much like that of any coloured diamond, can be attributed to the diamond’s exposure to radiation whilst being formed.

The rarest green diamonds in the world include the Ocean Dream diamond and the Dresden Green Diamond. The Dresden Green Diamond is a 41-carat stone which is suspected to have originated in the Kollur mine in India. Named after the capital of the German state of Saxony, it has been on display for the last two centuries and is now shown in the New Green Vault at Dresden Castle.

4. Orange Diamonds

Although many have speculated on the subject, the true cause of the colouring of the orange diamond remains unknown. Gemologists at the William Goldberg Diamond Corporation have cited nitrogen as the affecting element, whilst Harry Winston believed the presence of hydrogen to be responsible.

Amongst the most famous and most valuable orange diamonds in the world are the Pumpkin Diamond and the Koi Diamond. Weighing 5.54 carats, the Pumpkin Diamond was mounted in a ring designed by Harry Winston in the late 1970s and worn by Halle Berry during the 2002 Academy Awards ceremony. The Koi Diamond is a 32-carat stone of multiple hues (a combination of orange and white) which has been cut to resemble Japan’s most celebrated fish – the Koi.

3. Pink Diamonds

Pink is one of the most popular and highly-demanded colours of diamond in the world. Much like the orange diamond, the source of the colour in the pink diamond has been subject to speculation amongst experts but still remains unclear. One of the most widely-accepted theories as to the origin of the colour states that in the process of the diamond being forced to the Earth’s surface, the structure of the stone is somehow altered, causing a deformation by which the stone absorbs light in a different way and emits a pink hue.

The most expensive pink diamonds in the world include the Pink Star Diamond and the Graff Pink Diamond. At 24.78 carats, the Graff Pink Diamond has been regarded as one of the greatest diamonds ever discovered and smashed records when it was sold for $46 million by Sotheby’s auctioneers in Geneva in 2010. Before its sale, it was expected that the stone would find itself upon the list of the top ten most expensive diamonds in the world. After fetching the magnificent sum that it did, it soon became the most expensive single jewel ever sold at auction at that time.

2. Blue Diamonds

One of the rarest colours of diamond in the coloured diamond family, the colouring in blue diamonds is caused by the trace amounts of boron that are present which contaminate the crystalline lattice structure.

Amongst the most famous blue diamonds are the Wittelsbach-Graff Diamond and the Hope Diamond, both of which have a fascinating history. The Wittelsbach-Graff Diamond originated as the Wittelsbach Diamond and was purchased by Laurence Graff in 2008 for £16.4 million. Graff later renamed the diamond after revealing he had had it cut by three experts to remove flaws, reducing the overall weight by more than 4 carats but producing a deep-blue diamond with internally flawless clarity. Controversy still surrounds Graff’s decision, as critics claim the diamond has been altered to such an extent that it is now unrecognisable, compromising its historical integrity.

The Hope Diamond remains one of the most famous jewels in the world, with records of ownership dating back almost four centuries. Originally a larger stone known as the Tavernier Blue Diamond, its origins have been traced to India. Purchased by French gem merchant Jean-Baptiste Tavernier in 1666, the stone was cut to produce the French Blue Diamond, which was sold to King Louis XIV in 1668. Stolen in 1791, it disappeared without trace and was recut. In 1839, the largest portion of the stone reappeared in the catalogue of a gem collection owned by a London banking family with the surname Hope, and so the stone adopted the same name.
After being passed through numerous owners, it was acquired by Harry Winston in 1949, who toured it for several years before donating it to the National Museum of Natural History in 1958. The Hope Diamond remains on permanent exhibition in the museum, and was last reported to be insured for $250 million. It has long been rumoured to carry a curse to the effect that those who wear it or own it suffer misfortune and tragedy.

1. Red Diamonds

With less than 30 red diamonds known to have been found, the red diamond is considered to be the rarest form of coloured diamond in the world, and therefore the most expensive. Red diamonds have the most expensive price per carat, with most being priced at hundreds of thousands of pounds/dollars per carat. Being the rarest colour, they are also extremely difficult to find in large sizes, and are mostly found weighing less than 1 carat. Despite decades of research into possible causes for the colouring in red diamonds, scientists have not managed to produce a conclusive theory.

The most famous red diamonds in the world include the Hancock Red Diamond and the Moussaieff Red Diamond. The Moussaieff Red Diamond is the world’s largest known red diamond, making it the rarest of them all. Originally measuring 13.9 carats and named the Red Shield Diamond, the stone was discovered in the 1990s by a Brazilian farmer in the Abaetezinho river. It was then purchased and cut by the William Goldberg Diamond Corporation, before being purchased in the early 2000s by Shlomo Moussaieff, an Israeli-born jewellery dealer in London, who gave it its new name.