Diamonds can be graded more comprehensively than any other gemstone because of their great value. The best known Diamond grading system is one developed by the Gemological Institute of America (GIA) known as the International Diamond Grading System™. It has been adopted by leading, international gemological laboratories and uses Carat (weight), Color, Clarity and very importantly Cut (the Four Cs) as a way to objectively compare and evaluate Diamonds.

1. Cut

Cut fuels the Diamond’s fire, sparkle, and brilliance

The traditional 58 tiny facets in a Round brilliant Cut Diamond, each precisely cut and sharply defined, may be only two millimeters in diameter. But without this precision, a Diamond wouldn’t be near as beautiful as it is. Without a doubt, the allure of a particular Diamond depends more on cut than anything else.

Though extremely difficult to analyze, the cut of a Diamond has three attributes: brightness (the total light reflected from a Diamond), fire (the dispersion of light into the Colors of the spectrum), and scintillation (the light "flashes" or "sparkles", when a Diamond moves).

As a value factor though, cut refers to a Diamond’s proportions, symmetry, and polish. For example, look at a side view of the standard round brilliant. The major components, from top to bottom, are the crown, the girdle, and the pavilion. A round brilliant cut Diamond can have 57 or 58 facets, the 58th being a tiny flat facet at the bottom of the pavilion, known as the culet. The large, flat facet on the top is the table. The proportions of a Diamond refer to the relationships between table size, crown angle, and pavilion depth. A wide range of proportion combinations are possible, and these ultimately affect the stone’s synchronicity with light. The GIA assigns an overall Diamond cut grade ranging from Excellent to Poor.

Verena Pagel-Theisen, Diamond Grading ABC: Handbook for Diamond Grading, 1980, p.154

Every facet in an Ideal Cut Diamond must be placed at precise angles and contain precise proportions. This ensures an Ideal balance between maximum brilliance and dispersion of light. Any discrepancy from these proportions will disrupt the even distribution and dispersion of light within the stone, resulting in a loss of sparkle. The mathematical calculations to cut facets that reflect the most light were established in 1919. Stones cut to this specification can be scientifically tested to exhibit Triple Excellence Light Performance (excellent fire, brilliance and scintillation) to be designation Ideal Cut. When the angle of the Diamond's facets and proportions vary from the 1919 calculation, the stone’s cut is assigned descriptions from Ideal / Excellent through Poor.

A well-proportioned pavilion is especially important to a Diamond's brilliance. Brilliance is the brightness created by the combination of all the white light reflections from the surface and the inside of a polished Diamond. If the pavilion is too deep or too shallow, it causes light to strike outside the critical angle - the largest angle at which light rays inside the Diamond can escape - causing the light to exit through the pavilion rather than reflecting back to the eye as brilliance. The image below illustrates an Ideal Cut Diamond's light being reflected back up through the table maximizing the stone's brilliance.

Diamond Reflection


The standard round brilliant Diamond shape dominates the majority of Diamond jewelry. However Diamonds are offered in a variety of shapes to please one's individual preferences. Not to be mistaken or confused with cut, shape as it is most often described as viewed from above, is very much a personal preference. The unique characteristics of each shape determine the overall quality of the Diamond. Other Diamond shapes are known as fancy and include the marquise, pear, oval, and emerald cuts, hearts, cushions, trilliants, and more. For a complete reference of gemstone shapes see Amoro gemstone cuts.

2. Color

The Color of the Diamond is all about what you can't see

Diamonds are valued by how closely they approach Colorlessness – the less Color, the higher the value. Most Diamonds found in jewelry run from Colorless to near-Colorless with slight hints of yellow or brown.

Diamond Color Comparison

GIA's Diamond color-grading scale is the most widely accepted grading system. The scale begins with the letter D, representing colorless, and continues, with increasing presence of color, to the letter Z. Diamonds are color-graded by comparing them to stones of known color under controlled lighting and precise viewing conditions.

Many of these color distinctions are so subtle that they are invisible to the untrained eye. But these slight color differences make a very big difference in Diamond quality and price. A Diamond must have a color value of H or higher to be considered for the Amoro Eternitymark® Diamond designation.

3. Carat

One expects a larger Diamond to be worth more than a smaller one all things being equal

Diamonds and other gemstones are weighed using metric carats with one carat weighing about the same as a small paper clip, or 0.2 grams. Just as a dollar is divided into 100 pennies, a carat is divided into 100 points which means that a Diamond of 50 points weighs 0.50 carats. But two Diamonds of equal weight can have very different values depending on the other three characteristics of a Diamond’s 4Cs: clarity, color, and cut. The majority of Diamonds used in fine jewelry weigh one carat or less.

Diamond Size Comparison

Because even a fraction of a carat can represent a considerable difference in cost when purchasing Diamonds, exact precision is crucial. In the Diamond industry, weight is measured to a thousandth of a carat and rounded to the nearest hundredth. Each hundredth is called a point (a 0.25 ct. Diamond would be called a “twenty-five pointer”). Diamond weights greater than one carat are expressed in carats and decimals. (For instance, a 1.08 ct. stone would be described as “one point oh eight carats,” or “one oh eight.”) Because they become increasingly rare with size, Diamonds of the same quality increase in value by their weight as well as with their size. For example, a two carat Diamond would be valued more than double the price per carat than a one carat Diamond of the same cut, color and clarity.

Note: Screen resolution may alter the reproduction size of the chart above. This carat/millimeter sizing chart is meant for comparison purposes only.

4. Clarity

Diamond Clarity refers to the absence of internal inclusions or external blemishes

Because Diamonds are created deep within the earth, most contain unique birthmarks called inclusions (internal) and blemishes (external). Diamonds with very few birthmarks are rare and, of course, rarity affects a Diamond’s value. Using the International Diamond Grading System™, created by GIA, Diamonds are given a clarity grade that ranges from flawless (FL) to Diamonds with more prominent inclusions (I3).

Every Diamond is unique. But none are absolutely perfect even though some come close, even under 10x magnification. Known as flawless Diamonds, they are exceptionally rare. Most jewelers have never even seen one.

The GIA Clarity Scale contains 11 grades, with most readily available Diamonds falling into the VS or SI categories. In determining a clarity grade, GIA considers the size, nature, position, color or relief, and quantity of clarity characteristics visible under 10x magnification.

Diamond Clarity
  • Flawless (FL)
    No inclusions or blemishes are visible to a skilled grader using 10× magnification
  • Internally Flawless (IF)
    No inclusions and only minor blemishes are visible to a skilled grader using 10× magnification
  • Very, Very Slightly Included (VVS1 and VVS2)
    Inclusions are difficult for a skilled grader to see under 10× magnification
  • Very Slightly Included (VS1 and VS2)
    Inclusions are clearly visible under 10× magnification but can be characterized as minor
  • Slightly Included (SI1 and SI2)
    Inclusions are noticeable to a skilled grader using 10× magnification
  • Imperfect (I1, I2, and I3)
    Inclusions are obvious under 10× magnification and may affect transparency and brilliance

Amoro - A "Cut" Above

What is the most important "C"?

While the Four C’s on a grading report are a good starting point, they do not effectively display the true beauty of a Diamond. The qualities of color and clarity naturally occur and belong to each Diamond. The qualities of cut and carat weight however are dependent on the mastery of Diamond jewelers - those who create the most beautiful Diamonds. The "C" for cut is without debate of the greatest importance. The cut determines how brightly a diamond sparkles with the fire and brilliance found in all Amoro Diamonds.


Trust in your diamond and your jeweler.

Amoro calls upon lifetimes of expertise to select Diamonds that represent the best combination of color, clarity and cut which add up to the most beautiful Diamond offered for the price. For more on Amoro Eternitymark® Diamonds, click here.