They contain impurities within the chemical composition and different impurities will cause different colours to form within the structure of the diamond. The more impurities, more intense the colour.
Almost all diamonds have a bit of colour in them - this is shown on a Diamond Certificate under colour grading. ‘White’ Diamonds usually have a yellow or brown tinge - these are grade from D to Z, D being a rare colourless diamond and Z being a low quality coloured diamond.
Fancy Diamonds are also graded by GIA in terms of colour, the colour rating scale differs for diamonds with deep hues. They are given a grade for the intensity of the colour, these include; Fancy Light, Fancy, Fancy Intense and Fancy Vivid. They also have a detailed description of the colour hues, for example, ‘Fancy Yellowish Diamond’, ‘Fancy Pink Brown’ and ‘Fancy Light Blue-Green’. Brown (also known as Champagne) Diamonds are becoming more popular as they are lower in price, as are Fancy Yellow Diamonds. As the colour intensifies, so does the value.
Coloured diamonds occur naturally, meaning that some colours are more common than others. Prices of coloured diamonds do tend to range in prices, often being higher than colourless diamonds. Though, lab-grown diamonds are not only an option but also more affordable and just as beautiful. The more intense the colours are, the higher the price will be. So, it’s possible to artificially enhance the colour of a diamond by irradiating or heat-treating a diamond. Quality Diamonds do not sell artificially enhanced diamonds.
Fancy Diamonds have become super trendy at the minute, along with Birthstones. They come in every colour you could imagine, even black, and they all are formed in different ways.
Yellow Fancy Diamonds are created through the addition of Nitrogen.
The presence of Boron when the stone forms, leads to stones that range from a light blue to a rich deep blue.
The pressure during formation changes the crystalline structure, resulting in a rich red colour - which is one of the rarest Fancy Diamonds due to how rarely they occur naturally.
It is thought that Pink Fancy Diamonds are formed in a similar way to red as they are also just as rare and sought after. Around 90% of these diamonds have only been found in one mine - the Argyle Diamond Mine.
Green diamonds are thought to result from the irradiation of the diamond while it was forming in the earth, the effect of the radiation causes electrons in the crystalline structure to change slightly resulting in the colour green.