Like with colourless diamonds, the 4 Cs of fancy colour diamonds represent the four main components of the stone: Cut, Colour, Clarity and Carat Weight. However, the grading of coloured diamonds is a complex and specialized process which needs highly trained graders from authorized laboratories.
What Are Fancy Colour Diamonds?
Let’s start with the basics. Diamonds in the normal colour range are colourless through light yellow and they are graded using the D to Z colour grading scale.
However, the world of diamonds is not limited to this scale. There are rare specimens that come in a variety of colours, including blue, green, pink, yellow and red. Such diamonds are commonly called “Fancy Colour Diamonds” or simply “Fancy Diamonds”.
Colour of Fancy Diamonds
As mentioned above, the grading of fancy diamonds is a specialized process. Unlike colourless diamonds, when grading coloured diamonds cut quality is not the most important of the 4 Cs.
When it comes to fancy colour diamonds, the only thing that matters the most is the colour rarety.
Actually, cut quality is also important, but it is a cut quality that brings out the stone’s colour, and not the cut that maximizes symmetry and brilliance.
When talking about colourless diamonds, the value is based on the absence of colour, meaning colourless diamonds are the rarest. Just the opposite happens with fancy colour diamonds, their value increases with the strength and purity of the colour.
Fancy colour diamonds come in almost any colour you can imagine. The most valuable colours are red, pink, blue and green. Diamonds with red, green and blue medium to dark tones are extremely rare. Even very slight colour differences can have a big impact on the price of fancy diamonds.
In general, diamonds with a noticeable hint of any other hue than yellow and brown are considerably rarer. Even in light tones, as long as they show colour, diamonds are qualified as fancy colour diamonds, which is why the GIA fancy colour diamond colour-grading system is designed to accommodate the fact that not all coloured diamonds have the same saturation.
Diamonds with red or reddish colours, also known as “rose-coloured” are extremely rare and very highly valued. In this range, pure pinks are more popular than diamonds that have orange, purple “mauve”, grey or brown colour.
Blue diamonds are extremely rare as well. Their colour is caused by the presence of boron impurities, meaning the more boron, the deeper the blue colour; however, they generally have a slight hint of grey.
Green diamonds are typically light in tone. Their colour is often muted with a greyish and brownish cast. Green diamonds get their colour when radiation displaces carbon atoms from their normal position in the structure. This can happen naturally when diamonds deposit lies near radioactive rocks or artificially as a result of treatment.
Brown is the most common fancy diamond colour. Brown diamonds range in tone from very light to very dark. They were considered good only for industrial use until the 1980s when they began to appear in the Argyle mines, Australia. For marketing purposes, the Australians gave them names like “cognac” and “champagne”. Nowadays, brown diamonds are popular in many mid-level jewellery designs.
The second most common fancy diamond colour is yellow. In trade yellow diamonds are called “canary” for the same marketing purposes.
Fancy white and grey diamonds also exist. White ones have milky white colour and display beautiful flashes. Greys are getting popular for vintage style jewellery designs.
Clarity of Fancy Diamonds
Since colour is the dominant value factor when talking about fancy diamonds, inclusions are tolerated more than in colourless diamonds.
Gemstones with many inclusions that are of low clarity grade are still highly prized if they are fancy colour. The only reason which can lower the diamond’s value is inclusions that threaten the gem’s durability.
Cut and Carat Weight of Fancy Diamonds
The other 4 Cs of fancy colour diamonds are cut and carat weight.
In general, large fancy colour diamonds are rarer and more valuable than small ones, which is also true for all other diamonds. But cut and size can greatly affect the colour of a fancy diamond. The larger a diamond is or the deeper is the pavilion, the richer and more intense its colour.
The style of the cut can influence the intensity of colour as well. For example, there are certain cut styles (typically mixed cuts) which intensify the yellow colour in diamonds.
Cover image credit: Q Diamond