Feather Inclusions: Definition, Risks, and How to Spot Them

Getting finicky about feather inclusions...

Inclusions can make or break a diamond’s overall sparkle and appeal, and feather inclusions are no exception. Like cracks and fissures in the earth, feather inclusions can extend far across a diamond both internal and externally, and they can even harm the stone’s durability.

Sparkle is a key factor in a diamond’s charm, and feathers can inhibit optimal light performance. Let’s dive deeper into feather inclusions and how they impact a diamond so you can readily identify their effects as you shop.😊

A Guide to Feather Inclusions in Diamonds
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Basics: What is a diamond feather inclusion?

Feather inclusions are incredibly common, and they can be found in most diamonds on the market. A “feather” is a fracture or crack that interrupts a diamond’s orderly, carbon-lattice structure.

Feathers in a diamond can be white or dark colors, and they can be found both within the stone as well as on its facets. They may be too small to notice with the naked eye or large enough to extend from inside the diamond to the stone’s surface!

You’ll typically come across feathering in diamonds with VVS to I clarity grades. In most cases, feathers can go entirely unnoticed when viewing the diamond from above but are more apparent when viewed at certain angles.

How do feather inclusions form?

So why do some diamonds have feather inclusions? How do they form? There are two main ways feather inclusions form within diamonds: naturally during the diamond formation process and unintentionally during the mining, cutting, or polishing processes.📝

During diamond formation

During the formation process, carbon faces intense heat and pressure in the earth’s mantle for millions of years before forming into diamond. Eventually, a process known as “emplacement” occurs, which means large rock sections push the diamond violently upward toward the surface, where it’s found in mines.

The violent formation process, as well as the harsh upward movement, can both cause feathering to appear on a diamond. As such, this feathering is natural and predates any man-made inclusions or blemishes.

During commercial processes

Diamonds can also obtain feathering via mining, cutting, or even polishing processes. Each process requires the use of powerful tools that can strike or cut a diamond, creating a fracture on or within the stone. As if the explosive and forceful efforts of mining weren’t dangerous enough, diamonds must then undergo cleaving, bruting and polishing processes to reach their final, desired shape.

There’s no reliable way to tell how a diamond’s feather inclusions were created, but both types can impact sparkle and durability.

How can we spot a feather inclusion in a diamond?

Sometimes, locating a feather inclusion is as simple as closely inspecting a diamond yourself, but it’s often not that easy. Here are a few ways to identify feather inclusions within your diamond so you can make an educated buying decision:

On a plotting diagram

Diamond Feather Inclusions on a Diamond Plot
Blue Nile SKU: LD18334757 | GIA Report: 6395876597

If your diamond has a grading report—such as those provided by the GIA, AGS, etc.—you can actually locate feather inclusions easily! Laboratories include a “diamond plot” within each grading report that maps out all inclusions, blemishes, and other characteristics of note.

Feather inclusions typically appear as solid red lines on a diamond plot. As such, you can readily locate where the feathers appear and look at the corresponding locations on your diamond. That way, you can see whether the feathers impact the stone’s brilliance or not.

Via high-res images and video

Nowadays, there are plenty of reputable diamond retailers that offer high-resolution images and videos for inspecting your diamond at home! With these images and videos that rotate the diamond under bright lighting, you can locate any feather inclusions that impact your stone’s overall brilliance

James Allen and Blue Nile are two major companies that provide high-resolution images and videos, and they both extend professional chat, phone, and email services to potential clients that allow you to speak to a diamond expert virtually.

With a jeweler’s loupe

A jeweler’s loupe offers 10x magnification so you can more readily locate feather inclusions. Under proper lighting, you should be able to see most feathers with a jeweler’s loupe. Be sure you view your diamond from multiple angles and take a close look at how it sparkles to identify feather inclusions.

With the naked eye

Not all diamonds with feather inclusions are eye clean, and you can often locate imperfections via careful examination. A close look from multiple angles may reveal a longer or broader feather inclusion, but smaller, hairline feathers are harder to spot if they’re not under the table of the diamond.

💡Make sure you have good lighting when inspecting your diamond so you can have the best environment possible for locating inclusions.

How do diamond feathers impact beauty and durability?

Feather inclusions can impact not only a diamond’s appeal and sparkle but its durability as well. We’ll discuss the factors that determine a diamond’s clarity rating and how they relate to overall beauty and durability.

Recap: The five factors of diamond clarity

To start, let’s review the five clarity factors that are used by diamond laboratories to bestow clarity ratings on each stone.

  • Size - The size of an inclusion determines how much it impacts a diamond’s clarity. Inclusion sizes can range from barely visible with magnification to large and extremely noticeable with the naked eye.
  • Nature - The “nature” of an inclusion refers to its type. Feathers are just one type of imperfection, but there are several other inclusions and blemishes that can occur naturally in and on diamonds. This category also takes into account whether a certain inclusion could pose a threat to the structural integrity of the stone.
  • Number - Number—quite literally—refers to the number of inclusions and blemishes a diamond presents. A larger number of inclusions means a lower clarity grade and vice versa.
  • Location - Location tracks where each inclusion or blemish appears in or on the diamond and how that placement impacts overall beauty and durability. Some locations, such as near the table’s center, are much more visible and make it hard to designate a stone as “eye clean”. Furthermore, inclusions under table and pavilion facets can impact the dispersion of light and decrease the stone’s overall grade.👨🏻‍🏫 Ideally, inclusions are found under the crown facets or near the girdle to avoid impacting sparkle.
  • Relief - Arguably the trickiest category, relief grades each inclusion’s visibility and color relative to the diamond. The more noticeable the inclusion, the lower the grade. Each diamond is graded on a color scale from D to Z, and so some inclusions stand out more on certain stones.

Beauty

Fire, brilliance, and scintillation are the cornerstone of a diamond’s glistening beauty.✨ Although it’s uncommon for feathers to impact sparkle, if they’re located in the right spot in the diamond or are abnormally large they can pose a threat to your stone’s shine.

Brilliance measures how well a diamond reflects and returns white light, which amps up that colorless sparkle. However, large or dark feather inclusions can cause “light leakage” where the light exits from either the sides or bottom of the diamond and decreases the gem’s brilliance.

Fire, or the presence of colored light, can also suffer at the hands of more noticeable inclusions. The goal with any diamond is to have a healthy balance of white and colored flashes mixed with minimal dark spaces. With too many feather inclusions, diffusing colored light isn’t as easy.

Again, feathers only impact sparkle in extreme circumstances, but it’s helpful to inspect each diamond carefully to ensure it’s eye clean and has the fire, brilliance, and scintillation you’re searching for. ⚠️Additionally, looking at a grading report alone won’t show you HOW inclusions and blemishes impact the diamond’s sparkle, and a poor cut may also be the culprit when it comes to a lack of white and colored flashes of light.

Durability

Even more important than a diamond’s sparkle is its durability, and the five factors of diamond inclusions play a role in a stone’s strength as well. Diamonds are the hardest gemstone available, and so we tend to assume they’ll last forever.

However, seemingly innocuous feather inclusions can turn into fatal flaws that cause weak spots in some situations. These weak spots can lead to chipping, cracking, and even a full breakdown of sections of the diamond in the long run!

Diamonds with feather inclusions located in the below areas are more at risk for structural damage down the line:

Near the girdle and points

Feather inclusions located near the girdle or any “points” of the diamond—think sharp corners and the culet—can potentially cause structural weakness. What’s more, feathers near the edges of the stone can cause small sections to break off.

Extended surface feathers

Feathers that start inside the diamond and actually break the surface of the stone are often noted as “cavities” on diamond plot diagrams, and they pose a series of risks. Inclusions that break the surface of a diamond leave the internal structure open to the elements and can weaken the rest of the gem. They’re also susceptible to damage when the diamond makes contact with a hard surface.

Across the girdle

If a feather inclusion starts in the lower half of a diamond and ends in the upper half, it is crossing through the girdle and posing a risk to the stone’s overall durability. A hard hit to a stone with a feather placed across the girdle can break the diamond, so this type of inclusion should be avoided if possible.

Cleavage planes

Feathers located on “cleavage planes” also pose a risk to durability. A cleavage plane is an internal weakness in a diamond that cutters often use to split diamond rough to begin the faceting process. If a feather inclusion runs through or along a cleavage plane, it enhances the weakness of that spot and can cause major breakage and chipping.

Feather inclusions and diamond clarity grade (Plus advice)

You have everything you need to make an informed buying decision regarding diamonds with feathers, but here are a few more key points regarding diamond clarity and feather inclusions before you go.

ALL inclusions are important

First, it’s crucial to remember that all types of inclusions can impact a diamond’s clarity grade, not just feathers. In fact, feather inclusions are not always “grade-setting characteristics”, and this designation depends on the severity of the five clarity factors we discussed earlier.

As such, follow the five factors to understand how your diamond was graded when it comes to clarity!

Feather inclusions and visibility

A diamond’s overall grade can indicate whether or not you will see that stone’s feather inclusions with the naked eye. For instance, Flawless (FL) or Internally Flawless (IF) diamonds do not have any inclusions that can be spotted under 10x magnification, so you won’t see feathers if you’re shopping in this clarity range.

In contrast, diamonds in the Very Very Slightly (VVS) and Included (I) ranges can have varying degrees of visible feathers. You probably won’t see the feathers without magnification in a VVS diamond, but they’ll become more apparent as you reach the I category. However, this all varies from diamond to diamond, so inspect each stone carefully.🔍

Pro Tip
If you're looking for a general rule to follow, stick with this: search for a stone that’s eye-clean. Having an eye-clean diamond means you won’t see any of its inclusions when staring down at your ring, and neither will the friends and family gawking at your new rock. Being eye clean also means the feather inclusions most likely aren’t in a place that can cause sparkle or structural issues.

For 1-carat diamond buyers

The 1-carat diamond is a hot commodity, and buyers love the perfection and well-rounded nature of this particular stone weight. If you’re searching for that ideal 1-carat stone, try to find a diamond with VS1 clarity or higher to avoid visible feathers.

However, that isn’t to say you absolutely will not find an eye-clean diamond in the SI1 to SI2 range, and we encourage you to search for one if you have the time. These stones may require extra digging and can have feathers that pose a higher durability risk, but if you do your research and remember the five factors you should be able to find a solid stone.

Pro Tip
If you’re interested in a fancy-shaped diamond with a large table—think emerald, baguette, or other step-cut gems—we recommend increasing your intended clarity grade by at least one level. These shapes are more inclined to show inclusions, so increasing your overall clarity can prevent noticeable feathers.

Bonus: Feather inclusions and fracture filling

Some diamonds undergo “clarity enhancements” to improve their overall clarity grade. For diamonds with feather inclusions, this process involves a method called “fracture filling”, which fills in the imperfections with a clear, glassy resin.

To fill a feather inclusion, experts must first drill a hole to reach the area. Then, they inject resin into the hole and cure it to fill the feather.

However, fracture filling does have some downsides, and we don’t recommend purchasing diamonds with clarity enhancements. For starters, while the feather inclusion may be filled, it doesn’t necessarily become invisible. The resin within the diamond can sometimes contain small air bubbles, or it may look like scratch marks within the stone.

Fracture filling also can change the way a diamond sparkles. While a diamond’s ideal fire, brilliance, and scintillation produces a balance of white, dark, and colorful flashes of light, resin-filled stones often present more colorful displays. Flashes of green and purple are sometimes visible in clarity-enhanced diamonds, which may make your stone appear fake.

Plus, filling fractures does not improve the durability of a diamond and, in fact, can have the opposite effect. For instance, resin doesn’t always withstand intense temperature fluctuations, meaning even routine cleanings can pose a threat of your diamond breaking apart under high temps. Fillings can also fall out or loosen under intense pressure, so clarity-enhanced diamonds must be handled very carefully!

Finally, while filling the feather inclusion may mask a large imperfection, the diamond now has a laser drill hole that can pose its own problems. As a result, the GIA and many laboratories do not grade these diamonds, meaning you’ll have to rely on less respectable reports.

Feather inclusions: Final thoughts

Although not all feather inclusions impact a diamond’s sparkle, it’s important to identify which ones may have an effect on brilliance and durability. However, almost all diamonds have inclusions, and feathers are tougher to spot than some other imperfections you may encounter on your diamond search.

Are you looking for a full guide to buying diamonds? Do you have your heart set on a particular carat size? Take a look at our thorough guides for buying 0.5, 1.0, 1.5, and 2.0-carat diamonds for more information regarding what to look for and how to shop smart!

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