Pink is a very desirable and sort after colour for diamonds, the strength and depth of the colour also increases the value of the diamonds, often pink diamonds will be cut in to heart shapes, and are popular as engagement rings. Natural pink diamonds are more valuable than colourless diamonds. Coloured diamonds are incredibly rare in nature, the vast majority of coloured diamonds are treated in a number of different ways to give the stone the colour. The colour in most natural diamonds is caused by natural phenomena within their atomic structure, which (whilst complicated) can be explained, however, the cause of the colour in pink diamonds remains a mystery. 

 Fancy pink diamonds are very rare in nature, but there is one place where 80% of all natural pink diamonds are found: Lake Argyle, North Western Australia. There is a vast diamond mine; The Argyle Mine that is owned by Rio Tinto and is the 4th largest diamond mine in the world, where over 20 million carats of diamond are mined every year. However, even for such a large number of carats only approximately 0.1% of the diamonds mined are classed as pink diamonds. 

 There are other diamond mines in the world where pink diamonds can be found, such as Brazil, Russia, Siberia, South Africa and Canada. However, none have the same level of production of pink diamonds as The Argyle Mine. 

 Natural pink diamonds are graded for clarity, cut, carat in the same way colourless diamonds are. The only thing which varies is the way in which the colour is graded, coloured diamonds have the colour graded based on the hue, saturation and tone. Grading the colour of fancy coloured pink diamonds is much more complicated than grading colourless diamonds. This is due to there being 3 categories which need to be judged for each stone. The hue of the stone is simply the colour, i.e pink there is 31 different hues. The saturation is the strength of the hue, i.e pink is a hue, a vivid fancy pink is a pink hue with very strong saturation, there is 7 different saturation levels. The tone refers to the shade or darkness of the colour, i.e the darker the diamond the stronger the tone. There are 11 different tones. 

 The colour grade that is given to a natural pink diamond will effect its value, with the most valuable diamonds having the strongest tone and saturation. So when we consider the small number of natural pink diamonds that are mined each year, and then the even smaller number that are suitable to be used as gemstones, it is easy to see how the value and, therefore, cost of a natural pink diamond with good clarity and cut will be more than a comparable colourless diamond. When we also take in to account the different tones and saturation levels, it becomes very clear how the prices for the deepest pink diamonds can set them into a league of their own.