What Is the Sharpest Knife in the World?

Knife on a Table
Knife on a Table

When it comes to knives, there is a lot to consider, from the blade material to the design and the intended use. But one question that often comes up is: what is the sharpest knife in the world? The answer may surprise you.

In short, the sharpest knife in the world is probably an obsidian knife. While impractical for use in a kitchen, the thinness of an obsidian blade makes its sharpness unparalleled. Obsidian blades have been used for many different things throughout history, from surgical tools to weapons. But there are other factors that can affect the sharpness of a knife, which we will explore in this article.

The Sharpest Knife in the World

The sharpest knife in the world is an obsidian knife. Obsidian is a naturally occurring volcanic glass that can be sharpened to a molecular edge. The way that obsidian breaks is known as a conchoidal fracture, which results in an incredibly sharp edge. In fact, the thinnest blades are three nanometres wide at the edge – 10 times sharper than a razor blade.

While obsidian knives are incredibly sharp, they are not practical for everyday use. Obsidian is brittle and can break easily, and the thinness of the blade means that it can chip or dull quickly. Additionally, obsidian knives are difficult to sharpen and maintain, and they are not suitable for cutting hard or dense materials.

If you are looking for a practical and durable knife that is also very sharp, there are several options to consider. Japanese knives are often considered to be some of the sharpest knives in the world, thanks to their thin, lightweight blades and high-quality steel. German knives, on the other hand, are known for their durability and versatility.

Factors Determining Knife Sharpness

When it comes to determining the sharpness of a knife, there are several factors to consider. In this section, we will explore the three main factors that determine knife sharpness: Material, Craftsmanship, and Maintenance.


The type of material used to make a knife plays a significant role in determining its sharpness. High-quality steel is often used in the production of sharp knives. The hardness of the steel is crucial, as harder steel can hold a sharper edge for longer. However, harder steel can also be more brittle and prone to chipping.

Other materials, such as obsidian and tungsten, are also known for their sharpness. However, these materials are not commonly used in the production of knives due to their impracticality and difficulty to work with.


The craftsmanship of a knife is another critical factor that determines its sharpness. The blade must be precisely honed and ground to achieve the desired sharpness. The angle of the bevel, the shape of the blade, and the thickness of the edge all play a role in determining the sharpness of a knife.

A poorly crafted knife may have a jagged edge, which can lead to dullness and chipping. On the other hand, a well-crafted knife will have a smooth, consistent edge that can maintain its sharpness for longer.


Proper maintenance is crucial for maintaining the sharpness of a knife. Regular sharpening and honing are essential to keep the blade sharp. A dull knife can be dangerous, as it requires more force to cut through food, increasing the risk of slips and accidents.

Additionally, proper storage and cleaning can also impact the sharpness of a knife. Storing a knife in a sheath or block can prevent it from becoming dull due to contact with other objects. Cleaning a knife after each use can prevent the buildup of food particles and debris, which can dull the blade over time.

How Sharpness is Measured

When it comes to measuring the sharpness of a knife, there are several methods used by professionals and enthusiasts alike. The most common method is the sharpness test, which involves cutting through a standardized material and measuring the force required to do so. The lower the force required, the sharper the knife.

One popular material used for sharpness testing is paper. A sharp knife should be able to easily slice through a sheet of paper without tearing or snagging. Another material commonly used is a tomato, which requires a delicate touch and sharp edge to cut through cleanly.

Another method used to measure sharpness is the edge retention test. This involves using the knife to cut through a material repeatedly and measuring how long it takes for the edge to dull. The longer the edge retains its sharpness, the better the knife’s edge retention.

It’s important to note that sharpness is not the only factor to consider when choosing a knife. Other factors such as durability, edge retention, and ease of sharpening should also be taken into account. Additionally, the intended use of the knife should also be considered when selecting the right tool for the job.

Safety Considerations with Ultra-Sharp Knives

When using ultra-sharp knives, it is crucial to prioritize safety to avoid any accidents. Here are some safety considerations to keep in mind when handling these knives:

  • Always cut away from your body. This rule applies to all knives, but it is especially important when dealing with ultra-sharp blades. Cutting towards yourself increases the risk of accidentally cutting yourself.
  • Use a cutting board. Avoid cutting on surfaces that are unstable or slippery. It is recommended to use a cutting board made of wood or plastic as they provide a stable surface to cut on.
  • Keep your knives sharp. A dull knife requires more pressure to cut through food, which increases the risk of the blade slipping and causing an injury. Use a honing rod or sharpening stone to maintain the sharpness of your knife.
  • Store your knives safely. Keep your ultra-sharp knives in a designated knife block or sheath to protect the blade and prevent any accidental cuts.
  • Avoid using your knife as a tool. Do not use the blade to open cans or packages, as this can cause the blade to dull or even break.
  • Be careful when cleaning your knives. Always wash your knives by hand with a mild detergent and avoid using abrasive sponges or steel wool. Dry the blade immediately after washing to prevent rusting.

By following these safety considerations, you can ensure that you are handling ultra-sharp knives in a safe and responsible manner.


In conclusion, the sharpest knife in the world is likely an obsidian knife. Obsidian blades are made from volcanic glass and are known for their thinness and sharpness. While they may not be practical for everyday use in the kitchen, obsidian knives have been used for various purposes throughout history.

When it comes to finding the sharpest knife for your needs, it’s important to consider the material, design, and purpose of the knife. While steel is a common choice for knife blades, other materials like tungsten and ceramic may offer better sharpness. Additionally, the design of the knife, whether it’s a folding or fixed blade, can impact its sharpness.

Ultimately, the sharpest knife for you will depend on your individual needs and preferences. Whether you’re looking for a knife for hunting, survival, or everyday use in the kitchen, it’s important to do your research and choose a knife that meets your specific requirements. With the right knife, you can achieve precision cuts and make your tasks easier and more efficient.

Frequently Asked Questions

What makes Obsidian knives so sharp?

Obsidian knives are made from volcanic glass, which is naturally formed when lava cools rapidly. The glass-like material is extremely sharp due to its thinness and the fact that it can be honed to a microscopic edge.

Are there any knives sharper than obsidian?

While obsidian is considered one of the sharpest materials, there are other materials that can be sharpened to a finer edge, such as diamond and tungsten carbide. However, these materials are not commonly used for kitchen knives due to their brittleness and high cost.

How does the sharpness of obsidian compare to a scalpel?

Obsidian blades are actually sharper than surgical steel scalpels, which are commonly used in medical procedures. This is due to the fact that obsidian can be honed to a sharper edge than steel.

What is the science behind the sharpness of the world’s sharpest knife?

The sharpness of a knife depends on various factors, including the angle of the blade, the type of material used, and the honing process. The world’s sharpest knife is made from obsidian, which is a naturally occurring volcanic glass that can be honed to a microscopic edge.

Is water really the sharpest blade in the world?

Contrary to popular belief, water is not the sharpest blade in the world. While water can erode and wear away at materials over time, it cannot be honed to a sharp edge like a knife.

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