When you hear the word “diamond,” what’s the first image that comes to mind? If you’re like most people, you might imagine a dazzling colorless gemstone—but did you know that truly colorless diamonds are extremely rare? Not only do most diamonds have a tint, but they can be vividly colored too! Today we’ll take at the look at how a diamond’s color is graded as part of the 4C’s.
The Normal Range
While diamonds can be any color of the rainbow and more, most fall within a certain spectrum. The vast majority of diamonds available today range from colorless to light yellow, brown or gray. You can think of this spectrum as the “normal range.”
Trace elements—like nitrogen or boron—that enter the diamond as it forms are mostly responsible for this range of color, but the stone’s crystal structure can also play a role. When intense pressure distorts a diamond’s crystal structure, hues like brown, pink, red and purple can appear. It’s only when a diamond’s chemical and crystal composition are close to perfect that colorlessness results. Otherwise, at least a faint tint will be detectable.
The Gemological Institute of America (GIA) has developed the most popular grading system in the US, so we’re going to use their scale.
For diamonds in the normal color range, an alphabetical spectrum from D (colorless) to Z (light yellow, brown or gray) is used. However, these letters don’t actually refer to specific colors. Instead, they simply mean that the diamond falls within a precise range of color. Therefore, two diamonds which are both graded H can actually look a bit different from each other.
Nonetheless, these grades are very technical. In fact, it’s typically only the experts who can tell a D diamond from an H diamond when it’s mounted in jewelry. Indeed, even diamonds graded K, L or M will usually appear quite colorless if they’re under 0.5ct.
When it comes to this scale, you can typically expect a diamond’s value to correlate with how colorless it is. The closer a diamond gets to a D grade, the more valuable it will be. However, when a diamond is graded below a Z, that’s no longer true. In fact, these special diamonds are valued for their color—not their lack of it! Let’s take a look at them next.
If a diamond doesn’t fall within the normal range, it’s considered fancy color. This includes black, blue, red, green, vivid yellow and much more. These diamonds are very rare in nature and are valued accordingly. Believe it or not, the entire world only produces a few thousand carats of fancy colors each year! When it comes to grading them, three qualities are considered: hue, tone, and saturation.
Hue is simply the diamond’s color category. These categories can be a single color (like red or blue) or some combination (like reddish-orange or bluish-green). Tone refers to the color’s lightness or darkness, while saturation (sometimes called intensity) is the color’s strength and purity. You can see the interplay between these qualities in the chart below.
The GIA fancy color scale ranges from faint to fancy deep, but you can’t look to the very top or very bottom of this chart to determine value. Instead, the most valuable grades are found near the middle, with fancy vivid being the most valuable of all. Why? As always, it’s about rarity. Fancy color diamonds with super high saturation and a light to medium tone are extremely hard to find, and their price will always reflect this.
However, it’s important to note that what these grades actually look like is completely dependent on the stone’s hue. Say you’re comparing two fancy vivid diamonds: one yellow and one blue. You may notice that the blue diamond appears paler and less saturated than the yellow one—yet they have the same grade! Why? Again, it’s all about rarity.
Believe it or not, each hue has it’s own spectrum of possible saturations and tones, so the grading scale is reinterpreted to reflect these differences. It simply wouldn’t make sense to grade blue diamonds by comparing them to how saturated or intense yellow diamonds can be. Instead, they are graded against other blue diamonds—which happen to be much harder to find than yellow ones!
At first, this may seem a bit complicated, but it actually helps to keep things simple! No matter the hue, fancy vivid is like a D rating on the normal range scale—it’s the most valuable simply because it’s the most rare.
If you ever start to get confused, just remember: grading isn’t about ranking how beautiful a given diamond is—a diamond of any hue, tone or saturation can be absolutely breathtaking. It’s all about rarity.
Thanks to modern technology, the color of a diamond can sometimes be changed! We won’t get into how this scientific marvel is achieved in this post—you can read our article about diamond treatments here—but these treatments do affect value, and I bet you can guess why. That’s right—we’re talking about rarity!
Though these treatments can make a diamond colorless, black, or practically any color of the rainbow, they will be considered less valuable than their natural counterparts—sometimes the difference in value can be well over 50%! As always, it’s because naturally colored and colorless diamonds are more rare. Nonetheless, these treatments can sometimes increase the value of a diamond well beyond what it would fetch had it not been treated.
If a diamond has undergone any treatments, it will be disclosed on the diamond’s grading report. This makes it easy to understand why two diamonds that look almost identical are valued so differently! Let’s dive into how that report is created.
The Grading Process
So, we’ve seen what the possible grades are, but how are they actually determined? After all, there are so many possible tints and colors, plus so many different conditions under which to view them. That’s why super precise methods have been developed by GIA and other labs around the globe. Even though these methods differ somewhat for the normal range vs. fancy color, they share most of the same steps.
Chiefly, diamonds of any color are graded relative to other diamonds of known color. These are called master stones, because they’re considered the standard for each hue. Master stones make it much easier to determine exactly where a given diamond ranks on the possible color scale.
Next, the lighting conditions are perfectly controlled. Graders typically work in a rather dark room with a special light source that’s optimized for color perception. Then, both the master stones and the diamond to be graded are turned upside down. Why? Because this minimizes reflections, which can alter the way the color appears.
However, fancy color diamonds are not turned upside down when graded. That’s because the way a diamond is cut can influence the way its color appears too! Therefore, it’s actually more accurate to grade fancy colors face up.
Today, special instruments have been developed to aid in the process of grading, but they’re not 100% accurate. Believe it or not, nothing can quite beat the precision and accuracy of the well-trained human eye—at least for now!
The Bottom Line
Beauty is in the eye of the beholder.
For diamond color, that saying has never been more true. Whether you’d like a rare pink diamond or a colorless classic, it’s all about what you find most alluring. The price, however, is a carefully considered valuation, and now you know how and why!
If you missed our last 4C’s post about cut, why not check it out now and find out how that quality is graded too? Next time, we’ll explain how a diamond’s clarity is graded, so be sure to stay tuned!
In the meantime, why not stop by one of our stores and see our collection of loose diamonds and diamond jewelry up close and personal—even under our microscope! Or, you can view our extensive diamond collection online here and our diamond jewelry here!
We hope to see you soon!