How Diamonds Get Their Colour

Diamonds occur in an array of colours – from pure whites and soft pinks and blues to brilliant hues of purple and red. No matter the colour, each diamond possesses a unique composition of chemical elements that have the power to dictate rarity, value and desirability. Read on to learn how nature creates the world's most radiant gems.

White Diamonds

White diamonds are the most common, falling into the largest colour spectrum on the Diamond Grading Scale, which begins with “D” colour, meaning totally colourless, and ending with “Z” colour, which is pale yellow or brown. The variable in this spectrum is the element Nitrogen – a D colour diamond completely lacks Nitrogen, with the Nitrogen content increasing along the spectrum. The vast majority of white diamonds mined today have a large content of Nitrogen, which classifies them within the end of the colour scale. Diamonds that fall within the E – F colour range are rare, therefore more valuable, as their chemical composition and crystal structure is made up almost only of carbon with only traces of Nitrogen.    

Yellow Diamonds

Coloured diamonds contain impurities or structural defects within the chemical composition. In the case of yellow diamonds, nitrogen is incorporated into their carbon crystal structure. These nitrogen impurities give a diamond its yellow colour as they modify light and absorb the blue part of the visible spectrum. Yellow diamonds that have a higher concentration of colour more intense than Z colour, as well as diamonds that exhibit colours other than yellow or brown, are considered “fancy” coloured diamonds. All fancy coloured diamonds follow the same colour grading scale: Fancy Light, Fancy, Fancy Intense, and Fancy Vivid. As the colour concentration increases within the stone, so does its value.   

Blue Diamonds

Blue diamonds are caused by impurities of Boron, a rare element in the Earth’s crust.

Many are modified with a grey secondary tone, or an uneven saturation with areas of colourless windowing, making natural blue diamonds with exceptional saturation and brilliance extremely rare.

Pink, Red & Other Coloured Diamonds

What makes a pink or red diamond? This is actually an impossible question to answer, as there is no impurity that causes its colour, only the evidence that these diamonds have a mutation within their crystal lattice that alters the stone’s molecular structure.

With enough of these “defect centres,” the diamond may take on different properties. For example, the diamond could absorb a certain wavelength of green light, resulting in a pink appearance. Other colours, such as green, purple and orange, occur from natural radiation and other common elements within the Earth. Diamonds are truly an anomaly of nature.

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