The cut of the diamond is a judgment of the quality of the shape, geometry, and finish of a diamond gemstone.

The Cut of the diamond is completely determined by the precision and quality of the methods used to cut and polish the diamond. Physicists, Material Scientists, and Gemologists have been studying diamonds for centuries to determine the exact dimensions of a diamond gemstone to get maximum light performance—the brightness, fire, and scintillation that makes diamonds so breathtaking. 

Note that “Diamond Cut” does not refer to the shape or make of the diamond gemstone.  The shapes that Ada offers can be seen here.

The Five Cut Grades

Gemological laboratories have 5 grades of cut: Ideal, Excellent, Very Good, Fair, and Poor. Ada Diamonds only offers diamonds with a Very Good or better cut grade.

Light Dances within the Diamond

To understand the differences between an excellent cut diamond and a mediocre cut diamond, you must first understand how light interacts with diamond, as light is reflected and refracted in a very different way than in air, water, glass, or other gemstones.   Diamond has a very high refractive index: light slows down in diamond, which creates the brilliance that sets diamonds apart.  

The Elements of Cut

BRIGHTNESS is how much light you see when you view a diamond. A well-cut diamond has very specific dimensions that reflect and return virtually all of the light that enters the diamond back out of the top of the diamond. Even in poor lighting, a diamond can appear very bright. A poorly-cut diamond leaks light out of the bottom and is dull or flat when compared to a well-cut diamond.

FIRE describes the rainbow of colors reflected by the diamond gemstone. Diamond has an extremely high rate of light dispersion. When white light enters the diamond, it is spread apart into distinct colors in a prism-like effect.  

SCINTILLATION defines the flashes of light that you see when the diamond moves.  This is also called the sparkle of the diamond.

PATTERN is the contrasting light and dark areas in a diamond gemstone. The better the cut of the diamond, the better the contrast is between dark areas and light areas. Mediocre diamonds have blurry gray areas, whereas the best-cut diamonds have very distinct contrasting patterns that are uniform throughout the diamond. This phenomenon is called Hearts and Arrows in Round Brilliant shaped diamonds.  

A perfect diamond, with no impurities and no defects, is completely colorless.  

As the purity of the diamond decreases, the color of the diamond increases.  The most common impurity in diamonds is clusters of nitrogen atoms inside the diamond.  Over 98% of mined diamonds have nitrogen impurities, which give diamonds undesirable tints of yellow and brown.  

In order to uniformly grade the color of diamonds, gemological laboratories have standardized on a range of letter grades of D-Z.  as explained in the chart below. Ada Diamonds is proud to only sell diamonds that are colorless (D-E-F) or near colorless (G-H-I-J). Perfectly colorless diamonds are more desirable and therefore command a premium.



Colored Diamonds

While it is extremely rare in nature, other impurities and crystal defects can result in a rainbow of colored diamonds: Red, Purple, Pink, Orange, Yellow, Green, Blue, Gray, and Black. These diamonds are classified as fancy colored diamonds, and less than 0.1% of mined diamonds receive this classification. Ada Diamonds can intentionally introduce trace elements into our diamond growth cells to create high quality colored diamonds. 

Clarity is a measurement of how many blemishes or inclusions are present in the diamond.

The lower the clarity of a diamond, the more imperfections in the diamond.   

From Flawless to included — Five Major Grades of Clarity:

The numbers after the major grade are a sub-grade, with the lower number being better.  So a VS1 is superior to a VS2, which is superior to a SI1. Diamond clarity is graded by viewing the diamond through a 10x magnification with a tool called a loupe.  

Flawless and Internally Flawless (FL, IF)

Both FL and IF diamonds have no internal inclusions visible with magnification.  IF diamonds may have very small blemishes present on the surface of the diamond, where as FL diamonds will have no internal or external imperfections.

Very, Very Slightly Included (VVS1, VVS2)

Imperfections are extremely difficult to locate with 10x magnification and impossible to see without jewelers tools.  

Very Slightly Included (VS1, VS2)

Imperfections are difficult to locate with magnification and not visible to the naked eye. A layperson would have difficulty finding inclusions even with 10x magnification.

Slightly Included (SI1, SI2) 

Imperfections are easy to locate with 10x magnification, but are very difficult (SI1) or difficult (SI2) to see without a jeweler's tools.

Imperfect  (I1, I2, I3)

Imperfections are very easy to see under magnification and can be seen with the naked eye. Imperfect diamonds are more susceptible to cracking or breaking during daily wear. The majority of mined diamonds are of Imperfect clarity.



Reducing Inclusions in the Lab

Because the conditions in which our diamonds are grown are more controlled than the chaos produced beneath the Earth's surface, Ada Diamonds only offer diamonds that are Slightly Included (SI) or better, with the vast majority of our diamonds having clarity grades of Very Slightly Included (VS) or Very, Very Slightly Included (VVS).


There are many types of inclusions in mined diamonds, but diamonds made in laboratories can have two types of inclusions:

FEATHERS are small fissures or cleavages in the diamond crystal. They occur when the crystal grows too rapidly under the Earth’s surface, or in a lab.

PINPOINT INCLUSIONS are microscopic pockets of non-diamond material present in the diamond that look like specks of dust in the diamond when viewed under a microscope. In lab diamonds, the foreign material is either graphite or metal. Pinpoint inclusions in mined diamonds can be one of two dozen types of different materials. 


A diamond shape is an expression of personal style. 

Ada Diamonds offers diamonds in thirteen gemstone shapes in both brilliant and step cuts. No shape is superior to another. Whether you’re interested in a brilliant cut with its triangular facets that capture and reflect the most amount of light, or a step cut with its large, stunning trapezoidal facets, Ada Diamonds guarantees that its diamonds are among the best cut in the industry.

This video clearly demonstrates the difference between the two cutting styles in two diamonds that have virtually identical overall dimensions. The Radiant and Princess Cut diamonds are brilliant cuts, whereas the Asscher and Emerald Cuts are step cuts.   

Ada can cut diamonds to custom specifications for antique, or non-traditional shapes for custom jewelry, or to be sold as a loose stone. Please inquire if you seek an uncommon shape.

Here is a printable sizing chart that allows you to see the true size of various carat weight diamonds of various shapes.

Ada Diamonds brings together human expertise and high technology to cut superior gemstones and exceptional jewelry.

No robot can cut and polish a beautiful diamond without human, and no human can thoroughly evaluate and precisely facet a rough diamond without technological support. 

We have perfected our cutting process to meet the exacting standards of our company and our jewelry, and do not use traditional cutting operations in India and China where 85% of all mined diamonds are cut and polished today. 

Our five-step process marries the best technology in the industry with the most talented artists in the world to produce superlative diamond gemstones.

1. 3D Scanning

A laser scans the rough diamond crystal from all angles to build an exact 3D model of the diamond. Our lasers are able to detect every inclusion and blemish inside the crystal, as well as extremely precise external dimensions.

2. Optimization Algorithm

This model is then fed into sophisticated software to guide our cutting teams to select what shape(s) should be cut from the rough stone. Some of our rough diamonds are cut into multiple gemstones, while others only yield one cut and polished diamond.  

3. Laser CNC Cutting

Our cutting team finalizes the shape and dimensions of the gemstone(s) and loads them into one of the most precise robots in the world. The robot cuts the most important facets of the diamond to ensure it has the most fire and brilliance. For a round brilliant, the CNC machine cuts 17 facets.

4. Expert Hand Polishing

Highly talented diamond cutters, with decades of experience, spend hours perfecting the diamond into a beautiful gemstone. First, they inspect the diamond for any flaws, weaknesses, or problems. If the diamond is acceptable, the cutter will cut the additional facets in the diamond, and then spend hours polishing each facet to the highest quality. For a round brilliant, the cutter makes a total of 57 facets.

5. Final Inspection

The diamond is then passed to the master cutter for final approval. If they do not approve of the diamond, the entire process starts over with a much smaller diamond being cut from the subpar diamond.

6. Independent Grading and Laser Engraving

Once the head cutter has approved the finished diamond, it is shipped to an independent gemological laboratory for evaluation.  This independent laboratory, which works with both mined and cultured diamonds, will evaluate the diamond and grade it on the 4Cs and also use a laser to engrave a unique ID on the girdle of the diamond.