Fancy colored diamonds are known worldwide as extremely rare. Unlike white diamonds which still exist in nature in large quantities,  fancy color diamonds constitute less than 1% of the quantity of rough diamonds  manufactured globally, every year, and this quantity is steadily shrinking. 
 
In order to classify diamonds as NATURAL loose colored diamonds, they are certified in  gemological institutes such as GIA, HRD, or IGI .

Once a stone has been graded and certified, the natural loose diamond will have its own personal ID which includes an ID number for the loose diamond, measurements of the loose diamond, weight, shape, clarity, polish, symmetry and fluorescence. 
 
The price of a natural loose diamond is effected by color, cut,  carat, clarity.

 Cut: Fancy loose color diamonds (unlike white diamonds) are polished in a different manner than white diamonds. This is done in order to emphasize the  color as much as possible.

Color: Fancy loose color diamonds can appear as one primary color, without any secondary hue - for example, fancy blue diamonds, fancy pink diamonds, etc.

When it appears as a single color, the price of the diamond will be  considerably more expensive than a diamond with a secondary hue - for example,fancy Brownish Greenish Yellow, fancy Orangey Pink, or fancy Grayish Blue.
 
The intensity grading system for fancy color diamonds differs than that of white diamonds. Unlike white diamonds, which range from the letter D-Z, fancy color diamonds are graded by Light, Fancy Light, Fancy, Fancy Intense, Fancy Deep , Fancy Dark, and Fancy Vivid. The stronger the color - the higher the price. 

---