A diamonds color grade tells how much color is in the diamond. A diamond that is totally colorless is worth more than a diamond with a hint of color.  Color grades range from a colorless “D” grade up to a yellow/brown color “Z”.  Any diamond with more color than "Z" is graded as "Fancy Color".  Fancy Colored diamond and are valued lower than white diamonds of the same cut and carat.

The following chart illustrates the color characteristics of the diamonds from colorless to yellow/brown.

Color grading is done by placing the diamond face down and comparing them to master stones under special lighting.  Emerald and Asscher cuts show more color than ideal cuts such as round brilliant.  Some diamonds may have fluorescence, and is not graded under Color. This is made easily visible under an ultraviolet light source such as a black light used in special effects.  Diamonds with fluorescence will glow under an ultraviolet light.  Fluorescence can be faint to very strong, and the most common fluorescent color is blue.  As blue is the complimentary color to yellow, the most common tinted color in diamonds, blue fluorescence can make yellowish diamonds look white or colorless.

There are many methods of enhancing diamond colors. Some are to whiten white diamonds and others are to enhance the color with diamonds with not-so-good color. At DiamondOction.com, we use color enhancement to create fancy colored diamonds only.  We do not use any methods to raise the grades of white diamonds. Such as enhancing a “G” color diamond to “E”.  The different methods we use to enhance the color in our diamonds are HPHT, Irradiation and Surface Enhancement.  All our items are clearly labeled as Enhanced on our item description.

High Pressure, High Temperature (HPHT)
HPHT is a process developed by General Electric in 1999 to color treat diamonds.  This process puts over 60 kbar (nearly 1,000,000 psi) of pressure on the diamond at around 1400°C (2550°F).  Diamonds treated with HPHT can transform into many colors including to pinks and blues.  HPHT can also be used to create white diamonds, however DiamondOction.com will only use this process to create fancy colored diamonds.  This treatment is permanent and will not be affected by cleaning or heat from setting repairs.

Irradiation (IRR)
Irradiation treatment involves exposing the diamond to electromagnetic rays to release electrons from their normal location to a more desirable location changing its color.  Neutron bombardment and electron bombardment are the two main irradiation methods practiced today.  Diamonds treated by irradiation produce many brilliant colors such as green, yellow, blue and reds. This color treatment is permanent and will not be affected during cleaning processes. However, blue or green enhanced colors could change to a yellowish color if high heat, 300°C (572°F) or more, is used during setting repairs.

Surface Enhancement (SE)
Surface Enhanced diamonds are chemically treated to change the color of a diamond to Brilliant colors. This is done by coating the diamond surface with a metal halide.  A similar technique used to coat some camera lenses that create the blue reflection.  This method can produce vibrant pinks and cognac reds.  Care should be taken with surface enhanced diamonds.  The coating can wear out during heavy cleaning or heat from setting repairs.

Heat Treatment (HT)
Heat Treatment or 'annealing' is done using a combination of chemicals (beryllium, borax, lead, tantalum) and heat to change the diamond's color.  Heating or "cooking" the diamond is done at temperatures ranging from 450ºC (842°F) to 1850ºC (3362°F) for 2 to 12 hours or more.  We only use this process to create our black opaque diamonds.  To check if a diamond has been heat-treated, one way is to look for the presence of small fractures within the stone that appear around natural mineral inclusions.  This treatment is permanent and will not be affected by cleaning or heat from setting repairs.