Fancy yellows are the most popular of all natural coloured diamonds. They are also the most commonly produced fancy coloured diamonds. It is estimated that around 60% of all natural coloured diamonds belong to the fancy yellow category. There are many misconceptions regarding fancy yellow diamonds and they have often been mistaken as a ''common'' coloured diamond or as a rare gem. This has led to a lot of confusion and misconceptions in terms of categorization.
The majority of yellows are located just below the centre of the value scale. At the upper end of this scale are some exquisite vivid diamonds that have reached up to 6 figures or more per carat in actions.

What makes a diamond yellow?

The yellow colour of a diamond is the result of nitrogen molecules absorbing blue light, making the diamond appear yellow (yellow is the complement of the colour blue). While in rough form a natural yellow crystal is usually cut into a large and a small stone. Larger stones feature a much more intense yellow than smaller cuts. Faint, very light and light yellows are not considered fancy colour diamonds. They are graded on the D-Z color grading scale, generally at the lower end of the scale.
Light yellow diamonds originated in South Africa's Cape Province. While not considered coloured diamonds, they have a quite unusual yellow hue. Their colour has led to the creation of a special category called Cape stones, meaning diamonds featuring this distinctive yellow hue, yet not sufficiently yellow to be placed in the ‘fancy’ colour category. 
Yellow coloured diamonds can be found in every intensity grade in the GIA grading scale. Yellow diamonds range from Cape stones, colours in the U-V - X-Y-Z range, fancy light yellow, fancy yellow, fancy intense yellow, fancy vivid yellow and fancy deep yellow.