While most diamonds are brown, yellow, or colourless, the rare, vividly coloured ones known as "fancy colours" are especially prized. The greater the rarity in colour, the greater the value. Fancy coloured diamonds are typically not very saturated, so hues, particularly vivid hues, that deviate from the common brown, tend to be highly sought-after.
Fancy coloured diamonds are available in both natural and lab-grown diamonds.
Grading Coloured Diamonds
The coloured diamonds are graded on the same 3 - carat, clarity and cut - of the 4Cs used to grade their colourless counterpart. Learn more about the 4Cs at The 4Cs: Natural and Lab-Grown Diamonds Explained .
The colour grading of fancy coloured diamonds is distinct: whilst the D-Z scale evaluates the absence of colour, fancy coloured diamond grading focuses entirely on the presence and quality of colour.
The Three Components of Colour
The process of grading coloured diamonds focuses on three primary components: Hue, Tone, and Saturation, which combine to form the colour description and the fancy colour grade.
| Hue | Tone | Saturation |
|---|---|---|
|
Hue refers to the diamond's basic colour, such as red, orange, yellow, green, blue, violet, and purple. |
Tone represents the lightness or darkness of a colour. Tones in the middle are generally more sought-after. Fancy coloured diamonds with tones that are excessively dark or overly light can make it challenging to accurately perceive colour. |
Saturation refers to the strength or purity of a colour. Generally, the more intense the colour, or saturation, the greater the value. |
When a description includes more than one colour, the predominant colour is stated last. For example, "yellow-green" and "green-yellow" represent different hues. "Yellow-green" means that green is the dominant hue, whereas "green-yellow" means that yellow is the dominant hue.
For hues with either darker and lighter tones, colours are often described with alternative hues, such as "pink", "brown" and "grey".
Fancy Coloured Grades
Fancy coloured diamonds are given a colour grade followed by their hue. For example, "Fancy Intense Blue" or "Fancy Vivid Purplish Pink".
Important notes about grading:
- For yellow diamonds that would hypothetically be "Faint", "Very Light" or "Light", they are graded under the colourless diamond system of D-Z.
- For brown diamonds that would hypothetically be "Faint" or "Very Light", they are graded under the colourless diamond system of D-Z.
- Black and opalescent white diamonds do not follow these colour grades and are described as either "Fancy Black" or "Fancy White". From a technical perspective, this is simply because black and white represent the absolute extremes of tone (dark and light), and they lack a traditional hue.
Colour Distribution and Treatment Disclosure
In addition to the colour grade, some certifiers, including GIA, provide a "Colour Distribution" and, if relevant, a "Colour Origin".
- Colour Distribution: "Even" colour distribution across the stone is generally more sought-after than "Uneven" colour distribution.
- Colour Origin: Colour treatment generally improves the colour of a diamond. Diamonds that are colour treated will state "Treated", whereas non-treated colours will state "Natural".
Fancy Coloured Natural Diamonds
Rare Colours
These fancy coloured diamonds are highly sought after with limited natural occurrence.
| Colour | Description |
|---|---|
|
Red |
Red diamonds are the rarest of natural, fancy coloured diamonds. Of the red diamonds, Purplish-Red is considered the most sought-after. The red colour results from structural irregularities within the crystal. Red diamonds are mostly found in Australia, Brazil and Africa. The most significant mine to produce red diamonds is The Argyle mine in Western Australia. This mine closed in 2020. |
|
Blue |
Blue diamonds are extremely rare, making up less than 0.001% of all recovered natural diamonds. The blue colour typically come from traces of boron trapped inside the crystal structure. Blue diamonds are mostly found in South Africa, Australia and in India, from the Golconda region, where the very first blue diamond, the "Hope Diamond" was discovered. |
|
Pink |
Like red diamonds, pink coloured diamonds typically result from structural irregularities within the crystal. Pink diamonds are generally found in the same areas that red diamonds are found, and are, in a way, red diamonds that are lighter in tone, and lower in saturation. |
|
Green |
The green colour results from natural radiation exposure over geological time. Untreated green diamonds are typically very light in colour. Most of the current production of green diamonds come from Africa and South America. Radiation exposure can be mimicked well by laboratories and as such, it can be hard to differentiate lab-grown green diamonds to natural green diamonds. |
|
Purple / Violet |
Like red and pink coloured diamonds, purple diamonds typically result from structural irregularities within the crystal. The violet colour is caused by high hydrogen content. Purple or violet diamonds are found various countries, including Russia and Australia. |
Other Colours
The most common within the Fancy Coloured Diamond category are those that represent the highly saturated versions of hues that are abundant in nature: yellow, orange, brown, and grey. These diamonds are classified as "Fancy" only when they exhibit colour saturation or tone that surpasses the deepest colour, Z, on the normal D-Z scale.
Unlike the exceptionally rare colours discussed above, the principle for these fancy colours is different: desirability is determined primarily by intensity rather than the colour itself. The more intense, pure, and vivid the colour, the more exceptional the stone becomes.
Black and opalescent white fall into the fancy category but occupy a unique position. They are not categorised as exceptionally rare in the same way as natural red or deep blue diamonds, and appeal to specific aesthetic preferences.
Coloured Lab-Grown Diamonds
Coloured lab-grown diamonds are available in virtually every colour found in nature, with chemically and physically identical properties to their natural counterparts. This allows for greater access to unusual colours by the public.
Lab-grown diamonds achieve colour through two primary methods: during the growth process itself, or through treatments applied after growth.
How Colour Is Created
Colour During Growth
Manufacturers can create specific colours directly during the diamond's formation by controlling growth conditions and introducing particular elements. For example, HPHT-grown diamonds are commonly produced in various colours, including deep yellow, by adjusting the environment during synthesis.
Colour Through Treatment
After growth, manufacturers may apply treatments to create or intensify colour. Three main treatment methods are used:
- HPHT Treatment: For example, HPHT can transform brown diamonds into other colours, such as yellow, orange, green, or blue. These treatments are stable and permanent under normal jewellery conditions.
- Irradiation and Annealing: Exposing diamonds to controlled radiation, sometimes followed by heat treatment, can create black, green, blue, yellow, orange, pink, and red colours. This mimics the natural radiation that colours some natural diamonds.
- Multi-Process Treatment: Combining HPHT treatment with irradiation and annealing produces an even wider range of colours, including pink and orange. This flexibility allows manufacturers to create nearly any colour to meet market demand.
Choosing Your Colour
Understanding how colour works in diamonds, from the colourless D-Z scale to the spectrum of fancy colours, allows you to make an informed choice based on your preferences and budget. Whether you're drawn to the extreme rarity of natural fancy coloured diamonds or the accessible beauty of coloured lab-grown diamonds, clarity about colour grading, origins, and treatments ensures your purchase aligns with your expectations and values.
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