F-color diamonds are in demand because they are colorless: the most common (and most affordable) of the truly colorless diamond grades.

When shopping for a diamond for an engagement ring, most people want it to be colorless. We talk about “white diamonds” but what we really mean is diamonds that are perfectly transparent with an absence of color, not even a hint of yellow. Most diamonds have a faint yellow tint thanks to nitrogen atoms in their atomic structure that absorb blue, leaving a slightly yellowish body color.

The difference between diamond color grades is so subtle, I could show you a tray of white diamond engagement rings set with a mix of D, E, and F color diamonds and you wouldn’t be able to separate them into three piles. Your favorite diamond in the tray of rings is just as likely to be an F as a D.

An F-color diamond is graded in a gemological laboratory upside down so that the grader can focus on the body color of the gem without being distracted by its brilliance, scintillation, and dispersion (the three characteristics that give a diamond its beauty.)

The D-to-Z diamond color scale created in the 1950s by the Gemological Institute of America starts at D, completely colorless diamonds, and goes through the alphabet to Z, diamonds that are light yellow or brown. (Fancy colored diamonds, which have more noticeable color than Z diamonds, have their own separate grading scale that describes their color hue as well as its intensity.)

Diamonds are found in a continuous color range from complete absence of color to faint color. Diamond color grades chop this smooth color gradient into discrete steps. There aren’t just D, E, and F colors, there is a spectrum of D-color diamonds with gradually more color until suddenly a boundary is crossed and one of them is a very light E-color diamond then more E diamonds, each with slightly more color until one is a very white F-color diamond. The difference at each step is almost imperceptible, even when viewed in the best possible conditions.

Drawing the lines between diamond color grades is very difficult. To make it a bit easier, every diamond’s color is evaluated in comparison to other diamonds with known grades called a diamond master set. That’s the only way to see the slight differences in color or absence of color that characterizes the color ranges that make up each of the GIA color grades.

To make grading diamond color as consistent as possible, gemological laboratories remove as many variables as they can. Since color is a perception that depends on the viewing environment, diamond graders use a standard light source and white background when comparing the color of a diamond to the set of diamond master stones. At GIA, at least two graders give their opinion on color grades (without knowing the other grader’s opinion.) If they disagree, a senior gemologist will also grade the gem. The color grade is determined when enough graders agree on one grade (the number depends on the size of the diamond.)

What does F color really mean? It means that this diamond, when placed upside down next to a diamond master set, can be seen by a trained professional to have slightly more color than the E color but slightly less than the G color diamond. The slight differences in color can only be seen consistently in comparison, face down, in a controlled environment.

Will you be able to tell that your diamond is an F-color when you wear it in an engagement ring? If your diamond is set in platinum or another white metal like palladium or a bright white gold, professionals will be able to see that your diamond is colorless but not its exact grade. They might guess E or they might guess G.

The difference that an F color makes to your diamond’s beauty is less noticeable than the difference that cut quality makes. But if you want a colorless diamond at an accessible price point, F-color is a good choice for your diamond.