Color refers to the natural body color of a diamond and not to the reflection of spectral colors that flash when a diamond moves. Most diamonds naturally exhibit slight hints of yellow, brown, or gray. This color is caused by natural trace elements of nitrogen that were present when the diamond formed under the Earth’s crust. The less color a diamond exhibits, the higher the rarity, and therefore the higher the value.  After cut, color is the next most important characteristic to consider when choosing a diamond.

Diamonds with less color allow more light to pass, releasing more brilliance and fire. A diamond acts as a prism by dividing light into a spectrum of colors and reflecting this light as colorful flashes called dispersion or fire. Similar to looking through colored glass, color in a diamond will diminish the spectrum of color, or fire, emitted by acting as a filter. A diamond with a higher color grade, i.e., one with less color, demonstrates more colorful fire.

The international gemological color scale begins with the highest rating of D for colorless, and travels down the alphabet to grade stones with traces of very faint or light yellowish or brownish color. Diamonds with grades D through F are considered "colorless," G through J are considered "near-colorless," K through M are "slightly yellow," and N through Y are referred to as “light yellow or brown.” Brilliant Earth only carries diamonds of superior color, ranged D-J.

• D: Absolutely colorless or "icy white". The highest color grade, extremely rare and most expensive.
• E: Colorless. Only miniscule traces of color can be detected by an expert gemologist in a controlled environment, a very rare diamond.
• F: Colorless. Slight color detected by an expert gemologist, but still considered a colorless grade, a rare, high quality diamond.
• G-H: Near-colorless. Color may be noticeable compared to diamonds of better grades, but offers excellent value.
• I-J: Near-colorless. Color slightly detectable when compared to diamonds of better grades, a good value.
• K-Y: Slight or obvious color. Not offered by Brilliant Earth.