When examining a diamond grading report, you may come across the term “knot” listed among the clarity characteristics. While the name may sound unusual, a knot is simply one of the many naturally occurring inclusions that can develop during a diamond’s formation. In most cases, a small knot has little or no impact on a diamond’s beauty and is only visible under magnification. Understanding what a knot is and how it affects a diamond can help you buy with greater confidence.
What Is a Knot Inclusion?
A knot is a diamond crystal that is enclosed within the host diamond but extends to, or reaches, the polished surface. Unlike a completely internal crystal inclusion, a knot becomes exposed during the cutting and polishing process because part of the crystal intersects the surface.
Since a knot is made of diamond, it has the same hardness as the surrounding material. However, because its crystal orientation may differ slightly from the host diamond, it can appear raised, transparent, white, or reflective under magnification.
How Do Knot Inclusions Form?
Natural diamonds form deep within the Earth’s mantle over billions of years under intense heat and pressure. During their growth, tiny diamond crystals may become trapped inside a larger growing crystal.
As the rough diamond is cut and polished, one of these enclosed crystals may become exposed at the surface, creating what gemologists call a knot. This is a naturally occurring feature and not damage caused during manufacturing.
What Does a Knot Look Like?
A knot may appear as:
- A tiny white or transparent crystal
- A slightly raised area on the surface
- A reflective inclusion under magnification
- A small crystal near the girdle or a facet junction
In many diamonds, knots are extremely small and can only be identified using a jeweller’s loupe or microscope with 10× magnification.
Does a Knot Affect a Diamond’s Appearance?
Usually, no.
Small knots rarely affect a diamond’s brilliance or sparkle because they are often located near the edge of the stone rather than directly beneath the table. Most diamonds with a knot appear perfectly eye-clean during normal viewing.
However, if a knot is unusually large or located in a prominent position, it may be visible under close inspection and could influence the diamond’s clarity grade. As with all inclusions, its effect depends on its size, location, relief, and number.
Does a Knot Affect Durability?
In most diamonds, a small knot does not present a significant durability concern.
Because the inclusion itself is diamond, it is extremely hard. However, during the polishing process, a knot can occasionally create minor polishing challenges due to differences in crystal orientation. In rare situations, if a knot is very large and protrudes from the surface, it may require careful assessment by a professional gemologist or jeweller.
How Are Knots Shown on a Grading Report?
On a GIA Diamond Grading Report, knots are plotted on the clarity diagram and listed in the Key to Symbols. Their position helps gemologists identify the diamond and contributes to determining the overall clarity grade.
The presence of a knot alone does not determine whether a diamond receives a VS, SI, or Included clarity grade. GIA evaluates the size, number, nature, position, and visibility of all clarity characteristics before assigning the final grade.
Knot vs. Crystal Inclusion
Although related, these characteristics are not identical.
- A Crystal is a mineral or diamond crystal that remains completely enclosed within the diamond.
- A Knot is a crystal that extends to the surface after cutting and polishing.
In other words, every knot is a crystal inclusion, but not every crystal becomes a knot.
Should You Buy a Diamond with a Knot?
In many cases, yes.
A small knot that is positioned away from the centre of the diamond is unlikely to affect beauty or everyday durability. Rather than focusing on a single inclusion, evaluate the diamond as a whole by considering:
- Cut quality
- Clarity grade
- Position and size of the knot
- Whether the diamond is eye-clean
- Certification from a respected laboratory such as GIA
Many stunning natural diamonds with excellent value contain small knot inclusions that remain invisible without magnification.
Final Thoughts
Knot inclusions are a natural result of a diamond’s remarkable geological journey. Although the term may sound concerning, most knots are tiny, stable, and have little effect on a diamond’s appearance or performance. When purchasing a certified natural diamond, it is important to assess the overall quality rather than focusing on a single clarity characteristic. A well-cut diamond with a minor knot can still deliver exceptional brilliance, durability, and lasting value for generations.
