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By Sam Thomas

What Are Black Diamonds?

03 March 2023

The mystery in a black diamond

The colour black is loved for its mystery, intrigue and its timelessness. To wear black is often seen as being sleek and stylish. Black diamonds are also associated with this for their artistic beauty and dark glamour.

Celebrities have embraced black diamonds too, wearing them on the red carpet and they have also been featured prominently in films, famously in Sex and the City 2 when Mr Big presents Carrie with a five-carat black diamond ring in 18ct white gold; “Why black?” she asks. “Because you are not like anyone else,” he replies. The ring symbolises Carrie’s energy and passion with a lovely mix of modern and traditional to symbolise their eternal love.

However, black diamonds have not always shared the limelight of their coloured and colourless diamond cousins. Until recently, black diamonds weren’t regarded as high-end gemstones at all. Black diamonds only really started to gain popularity in the late 20th century, when black diamond engagement rings and other black diamond jewellery started to appear.

The reason for this late arrival of black diamonds being classified as precious gemstones is largely due to the composition of a black diamond. Black diamonds have a huge number of inclusions — small blemishes that affect a gemstone’s appearance. For a black diamond it is believed to be caused by the presence of graphite, pyrite, and/or haematite – all grey to black minerals. The significant volume of these inclusions is enough to change the overall colour of the stone to black. In short, a black diamond is so full of inclusions that it paints the entire stone black.

High durability

Black diamonds are known for their durability, scoring a 10 (the highest possible) on the Mohs scale of mineral hardness which is what makes them ideal for an engagement ring which is worn every day.

The structure of a diamond is composed of solid carbon crystal with identifiable natural cubic lines. What makes a black diamond different is that it consists of many small crystals all stuck together in random formation. As a result, the inclusions that make up the colour of a black diamond also weaken the linear structure of the diamond crystal and therefore cutting and polishing them can be difficult. They also must be set with great care. Even so, black diamonds are still graded as a 10 on the Mohs scale.

GIA grading of black diamonds

There are two categories of black diamonds: natural black diamonds and treated black diamonds. Like almost all gemstones, the first type — diamonds that have a natural black appearance — are significantly more rare, valuable, and desirable. Natural-colour black diamonds are characteristically completely opaque, with a high lustre that gives the stones an almost metallic appearance. However, many black diamonds sold for jewellery and engagement rings have been heat-treated to induce the colour. They begin as grey, heavily included and fractured diamonds that are subjected to low pressure and high temperature treatment, which “graphitizes” the fractures, turning them black. A second process, known as artificial irradiation, is used on off-colour diamonds and can also produce a green hue which is so dark the diamond appears black.

When you are choosing a black diamond for your engagement ring it is critical to differentiate between natural stones and treated stones, especially as this will impact the price and the appearance of the diamond.

As treated black diamonds are quite common, this can mean that it is often difficult to tell the difference between a natural black diamond and a treated one. As with all high-end gemstones, if you are considering buying a black diamond engagement ring, loose diamond, or other jewellery, be sure to visit a reputable jeweller. The GIA (Gemological Institute of America) only grades natural black diamonds as a guarantee of their authenticity. We recommend you ask to see the GIA certificate and receive the original copy with your engagement ring purchase.

Black absorbs colour rather than reflecting it, and for “colour nerds” out there it is not classified as a colour at all, but we will leave that to artists and colour theorists to debate. Regardless, natural black diamonds are graded using the same system as other coloured diamonds, also known as fancy colours. The level of intensity measures the strength of the colour.

Generally, a fancy colour diamond – becomes more valuable as the colour intensity increases. The “Fancy” intensity indicates the diamond has significant colour. The shade of the colour is neither light nor too intense. The scale begins with Fancy Light and continues in the following order: Fancy, Fancy Intense, Fancy Vivid, Fancy Deep and Fancy Dark. Black diamonds are the exception to this and are found in only one colour intensity: Fancy Black.

Due to the concentrations and types of the inclusions being responsible for the colour, a natural black diamond may range from near-colourless to brown or “olive” green. Whilst these features give each diamond their character, it is important to verify that the colour is fully saturated and to check that there are not any obvious imperfections when looking at the stone with the naked eye.

Even though fancy black diamonds do not receive regular colour and clarity grades, the 4C’s (cut, carat, clarity, and colour) are still important. All these factors play a major role in determining the quality and desirability of a black diamond just as they do in white or other coloured diamonds. It is also essential to consider the shape of the diamond. Each diamond shape showcases the bold and unique appearance of black diamonds differently. It is a very personal choice which needs to match the style and personality of the wearer, as well as the design or setting of the engagement ring.

The design or setting of an engagement ring is the one that best suits the wearer’s taste, as it will be worn and loved for many years, generations even. To enhance the dark alluring beauty of black diamonds they are often paired with contrasting colourless diamonds and set in either 18ct white gold or platinum which further highlights the black colour. Black diamonds can also look great with rose gold or yellow gold depending on the wearer’s skin tone and preference.

Black diamonds and the engagement ring

A black diamond engagement ring is bound to garner lots of attention. Pair your stone with a beautiful, finely crafted setting for an engagement ring that will be cherished for years to come.

Showcase the black diamond by setting it with a contrasting colourless diamond halo or by framing it in a trilogy setting with diamonds either side. Black diamonds are also a beautiful option for a full or half circle diamond wedding band or eternity ring for the less traditional brides who are looking for something a little edgier.

Due to their opaque colour, gorgeous lustre and shine, black diamonds are also often incorporated into Men’s jewellery – rings, earrings, bracelets, and necklaces.

Natural black diamonds are by no means the rarest occurring colour in nature, their appeal is in the depth of their mystery.

While glamorous and unusual they are still relatively affordable compared to most other natural fancy coloured diamonds. Nonetheless, size, shape and cut are highly influential in determining their value and superior stones are especially precious, beautiful and quite valuable.

Rare and beautiful

When searching for the perfect black diamond, if you find any that are a significantly lower in price than other comparable black diamonds, the diamond has probably been coloured treated. The demand for treated black diamonds is lower as many people prefer natural black diamonds, as a result they are usually significantly less expensive. If you are looking at black diamonds for investment purposes, it would only be considered worthy if it were of substantial size or had exceptionally special features that would increase its demand in the marketplace.

Presently, pink, red, and blue diamonds are deemed the prime fancy diamond colours for investment – their supply is deteriorating and demand for them continues to rise.

Natural black diamonds are still rare, only being found in very few locations including Brazil and Central Africa. If looking for a dark gemstone, sapphires are a stunning option too. Black sapphires are made of corundum with inclusions causing the colour of the stone. They have an enigmatic deep appearance and are very hard – rating 9 of Moh’s hardness scale. Black sapphires have an alluring character and catch the light in interesting ways. Unlike natural black diamonds, black sapphires are found in abundant quantities, especially in Australia.

Black diamonds seduce us with their deep inky ambiguity, whether they are chosen as the centrepiece for a unique engagement ring or as a wedding band to contrast, complement, and add flair to a sparkling white diamond engagement ring. Black diamonds are a distinct and beautiful symbol of love which we hope you will adore now and for generations to come.