Diamond Color Grading


When understanding how to buy a diamond, it is important to keep your specific preferences and budget in mind. Diamond color is often considered the most subjective grade, and what you think of as acceptable will largely be a matter of taste. However, differences in a diamond’s color grade can have a significant impact on its value.

For example, two diamonds with the exact carat weight, cut, and clarity can differ in cost based on different color grades. Colorless diamonds are the most rare. And most diamonds will have color, such as a light yellow or brown hint.

When grading color, gemologists turn the stone upside down on a white surface. According to the AGS, “The diamond grader then skillfully decides the color grade based on the saturation of the color compared to the master set. This step requires good eyes and extensive experience.”

Keep in mind the following color grades:

  • D – Colorless:
    • This is the absolute highest color grade a diamond can get. It is considered the most rare and most valuable.
  • E and F – Colorless:
    • These diamonds are also considered colorless, but have very slight hints of color compared to a D color stone. The color is impossible to detect by the untrained naked eye. These diamonds are also quite rare and valuable.
  • G and H – Near Colorless:
    • These color grades mean that color is hard to identify. These diamonds will appear as colorless to the untrained eye and are considered to be of excellent value.
  • I and J – Near Colorless:
    • Still reserved for exceptional diamonds, these grades indicate stones that have a slight warmth and tone, usually imperceptible to the naked eye.  
  • K to M – Noticeable Color:
    • These diamonds have a hint of identifiable yellow or brown to the naked eye.


The color grading scale goes all the way to Z, but diamonds lower than M color are not often found on the market because of their low quality.

Another aspect of color is fluorescence, or how a diamond reacts to ultraviolet (UV) light. And fluorescence can be found in around 35 percent of diamonds. Diamonds with fluorescence will glow a faint hue under UV light. Blue is the most common, though colors including white, orange, and yellow, among others, are also possible.

A diamond’s fluorescence can be beneficial in some cases. For instance, a yellowish diamond with blue fluorescence may appear colorless. “In many instances, observers prefer the appearance of diamonds that have medium to strong fluorescence,” the GIA found.

However, if fluorescence is too strong or accompanied by a low clarity grade with many inclusions, your diamond could appear cloudy. This can impact value, but beauty is still a matter of the buyer’s personal preference.

Diamond fluorescence example

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