Diamond Buying and the 4 Cs, Part 4: Assessing Diamond Clarity
Diamond buyers often find assessing clarity challenging. Although inclusions may be difficult to see and identity, they can have a significant impact on a stone’s value, optical performance, and even structural integrity. Learn what determines diamond clarity and how professionals grade this property.
7 Minute Read
With so many factors, it's essential to learn more to avoid buying the wrong diamond for your engagement ring.
We'll introduce you to our diamond clarity chart, which contains information on clarity terminology and explains how professionals grade clarity. We'll also bring together all the Four Cs of gem grading — carat, color, cut, and clarity — and recommend combinations that work well.
What is Clarity?
Clarity covers all things in a stone that affect the free passage of light. Thus, gem graders consider transparency, inclusions, and surface blemishes when evaluating clarity. Many gemstones contain inclusions, including virtually all diamonds. However, some are so small they don't impact grading.
Inclusions in diamonds include things like minerals, some in crystal shapes and others in long needle shapes, and twinning wisps that form inside a stone. Gem cutters usually try to cut a piece of diamond rough to create a stone as free of inclusions as possible. Typically, inclusions can't be removed, though some treatments try to minimize their impact in faceted gems.
Interested in this topic?
This article is also a part of our Diamond Fundamentals Mini Course, in the unit The Four Cs of Diamond Grading.
Generally, the freer from inclusions, the more valuable the diamond. Nevertheless, geologists love inclusions in diamonds, since they reveal a lot about the Earth's formation. (The youngest diamond is 900 million years old). Some inclusions can be quite beautiful and interesting, too. Diamonds can contain gems such as garnet or diopside and, often, even mini diamond crystals. In some cases, diamonds contain diamond inclusions that contain diamond inclusions! They all fit, one inside the other, like a Russian matryoshka doll. Included diamonds can make fascinating pieces for mineral or gem collections.
Inclusions can also help gemologists distinguish natural diamonds from synthetic diamonds or diamond imitations. Natural diamonds contain a much greater variety of minerals and inclusions than synthetics do. Furthermore, synthetic diamonds don't contain natural crystal inclusions.
Diamond Clarity Chart and Grades
Professional gem graders use the following diamond clarity grades.
"Flawless" diamonds are flawless inside and out. At 10X magnification under a microscope, they have no visible blemishes or inclusions. (If a diamond has inclusions too small to see at this magnification, they have no effect on the clarity grade).
"Internally flawless" means that the stone has blemishes but no inclusions. Blemishes encompass things like scratches and nicks that exist only on the external diamond surface. Usually, they can be polished away and likely won't affect the clarity grade too much. On the other hand, inclusions like crystals and feathers (cracks) exist inside the stone. These have much more impact on the clarity grade.
Incredibly rare, flawless and internally flawless stones account for just 2% of gem-grade diamonds. Thus, they command high prices, especially in large carat sizes.
You'll find an enormous price difference between an F and an IF stone, like that between an IF and a VVS stone. As clarity grades go down, the price differences decrease exponentially.
Very Very Slightly Included (VSS)
VVS stones have minute inclusions, so small they're barely noticeable under 10X magnification. Most consumers likely can't tell the difference between F, IF, and VVS diamonds.
Any stone in the VVS range still has extremely high clarity and will command a premium price.
Very Slightly Included
VS stones occupy the upper-middle range of diamond clarity grades. They have minor inclusions, which means they don't interfere much with clarity, even though they're larger or more numerous than those in VVS stones.
Stones in the SI range drop into commercial-quality. The inclusions are noticeable at 10X magnification but most likely not with the naked eye. Still, an SI stone may appear cloudier and less brilliant, especially to someone familiar with fine jewelry.
Generally, buying I stones isn't a good idea, even though they're technically gem quality. I diamonds have inclusions obvious even to the naked eye. Furthermore, these inclusions may even affect the diamond's durability or wearability, especially I3 stones.
Clarity and Diamond Buying
Choosing whether to buy a Flawless or a Slightly Included diamond for your engagement ring can depend on the stone's other quality factors. The larger the stone, the more visible the inclusions, simply because you'll have more surface area to view. For stones much larger than one carat, look for a clarity grade of VS or higher. For stones one carat or smaller, VS or even SI grades are pretty standard. In small stones (those below half a carat), clarity doesn't matter as much. Color grades will be more noticeable.
When buying a diamond, it's essential to look closely at the stone. If you're buying online, always review magnified video of the diamond to ensure that its imperfections do not impact its beauty.
Evaluating Inclusions and Their Impact on Diamond Clarity
Diamond graders assign diamond grades by looking at stones under 10X magnification. When examining an inclusion, the most important consideration is size. Obviously, an enormous inclusion will have a much bigger impact on a stone's visual appeal than a small inclusion.
The quantity of inclusions also matters. Even tiny inclusions will make a diamond look unattractive if too numerous.
Location also affects the visibility of any inclusions. The worst location is the table facet. Since the table acts like a window into the stone, inclusions will be most visible there.
Some settings may hide inclusions located around the girdle.
Inclusions located directly above the culet can sometimes be reflected within the diamond. The result will make one inclusion look like many. Although reflections of unusual inclusions, like garnet crystals, may appeal to collectors, this effect typically lowers diamond value.
Reflections of inclusions above the culet will lower a stone's clarity grade more than if the inclusion were located elsewhere.
Inclusions located near an area with high facet density (like under the crown facets) will have less visibility, because the light reflecting off the facets will distract from them.
Some clear or white inclusions, like diamond crystals, have less of an impact on a diamond's appearance than darker inclusions, like diopside or graphite crystals. Generally, the closer an inclusion comes to the host gem's color and refractive index, the lower its relief or contrast. Therefore, in diamonds, clear or white inclusions have lower relief than dark inclusions.
Different types of inclusions impact diamond clarity to different degrees.
For example, twinning wisps are white strain marks that form when the diamond crystal changes direction while growing. Since they radiate outward from the center of the stone, they affect clarity greatly.
Pinpoints, on the other hand, are tiny crystals barely visible under 10X magnification. They will have little effect on diamond clarity.
Feathers and chips can also have significant impact on the stone, depending on their size and location. A diamond can have a high clarity grade, even if it has tiny feathers along the girdle. However, a large feather may cause the stone to crack. Such an inclusion will drop the clarity grade dramatically.
A diamond grading report should come with a plot or visual diagram of the stone's inclusions. (You can see examples of these to the left of the photos in the "Diamond Clarity Grades" section above). This plot helps identify the diamond and also helps the buyer understand the diamond's clarity characteristics.
Please note, a plot won't contain all inclusions in a diamond. (It would look like a mess). Only the inclusions that set the grade are plotted.
One inclusion, however, is always plotted: the laser manufacturing remnant. This artificial inclusion results from the use of a laser (of course) to treat high-relief inclusions. In cases where such an inclusion is highly visible, such as below the table, a laser may be used to make a small channel to the inclusion. This allows acids or bleaching agents to reach the inclusion and either dissolve or lighten it. Usually drilled perpendicular to the table, the channel looks like a white pinpoint from the face-up position. However, when viewed from the side, the channel will appear as a thin white line.
Carat, Color, Cut, and Clarity Working Together
The larger the carat, the more obvious the other qualities become. So, the larger the diamond you buy, the higher the color and clarity grades you should look for.
No matter the carat, color, and clarity of the diamond, always choose a cut grade of Excellent or, at the very least, Very Good.
Keep these points in mind:
- Always go with what looks best within your budget. These are recommendations, not hard and fast rules. Although two stones may have the exact same grades, they won't necessarily look the same.
- These recommendations have more to do with a stone's value than appearance. A particularly low grade in one of the Four Cs will diminish the value of a higher grade in another. Since the Four Cs work together seamlessly, a diamond will be a better deal and hold its value more if well rounded in all quality areas.
If you're not sure what's best, check out our recommendations to get the most from your engagement ring budget.
And, if you're buying online, it's essential to buy from a dealer that provides close-up video of your diamond. James Allen and Blue Nile have extensive databases of diamonds and offer magnified, 360° views of each one. We recommend them because they let you see for yourself how the diamond's clarity impacts its beauty.
Phoebe Shang, GG
A gem lover and writer, Phoebe holds a graduate gemologist degree from the Gemological Institute of America and masters in writing from Columbia University. She got her start in gemology translating and editing Colored Stone and Mineral Highlights for a professor based in Shanghai. Whether in LA, Taipei, or New York, Phoebe spends her time searching for gems to design and being lost in good books.
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