Cut, Color, Clarity, Carat

Cut, Color, Clarity, Carat are known as the 4 C’s of diamond grading

Cut

Cut, Color, Clarity, Carat

 

In the Cut, Color, Clarity, Carat equation, the cut of a diamond refers to everything man has done in the process of converting it from a piece of rough, natural diamond material into a finished gemstone capable of the beautiful brightness and sparkle which makes diamonds the most popular of all precious gems. The details of cut include shape, make, angles, proportions, optical precision, weight ratio, facet symmetry and final polish. These specifics all combine to determine how the diamond will appear as it travels through the world’s many lighting conditions.

Most Important. Least Discussed.
Although geometry is the most important component for diamond beauty in the Cut, Color, Clarity, Carat formula, it’s typically discussed far less than color and clarity in most places. One reason is that color and clarity grading are easily learned by new sales professionals. But understanding the many details of optics requires a stronger commitment, as well as foundations in geometry and physics. It’s worth noting that most diamonds are made to average quality and in-depth discussions about geometry would reveal that lack of quality in average stores. The fact that many grading labs include little or no information about the make only underscores the resistance to education felt in commercial markets.

Top Cut

Improves All.
Diamonds in the top few percent of the world’s cut actually improve in the other Cs: They appear larger for their carat weight, face up more colorless and clarity characteristics can be less visible. Most importantly, they explode with dazzling whiteness and rainbow colors, even away from jewelry store lighting where most diamonds go dark.

 Helps Size Appearance:
A diamond designed for the highest level of visual performance appears larger than diamonds of average cut quality because they are bright all the way from edge-to-edge, not just bright in the center.

 Helps Color:
A diamond with the critical angles and precision needed for highest performance has shorter ray-paths reducing face-up color; in some cases by multiple grades.

Helps Clarity:
A diamond planned for highest performance boasts superior brightness and scintillation, even when removed from jewelry store lighting, which helps to “mask” inclusions.

Laboratory Standards:
Different laboratories have radically different standards.  Please see our page on Grading Laboratories for more information.

Shape:
Brilliant and mixed shapes like round brilliant, princess and cushion, have a different “flavor” than step cuts such as emerald and asscher.

 

Color

Cut, Color, Clarity, Carat

Color in diamonds is caused by trace chemicals occurring in the earth where the rough crystals formed over millions of years.

D-Z Color Range
Most diamonds are graded using the GIA developed D-Z color grading scale where D is at the top, Z is notably yellow or brownish, and the letters in-between descend very gradually. DEF are considered colorless and GHIJ are considered near-colorless. The colorless and near-colorless ranges are the most popular among diamond buyers as the differences are extremely subtle. Below J, diamonds show progressive levels of “warmth” seen as a yellow or brownish tint.

Fancy Colored Diamonds
A small percentage of diamonds with more color saturation than Z are called “Fancy Colored Diamonds,” or FCDs. Yellow or brown FCDs run from light to vivid. Additionally, FCDs may be an altogether different color like pink or blue. All Fancy Colored Diamonds are graded using a different scale and approach than diamonds in the normal D-Z range.

Grading Color
Diamonds in the normal D-Z range are graded face-down, viewed through the side of the pavilion. This is because shape and cut quality both influence how light gets in and out of the diamond. Grading face-down allows for a neutral assessment of body color. The descending grades from D to Z are very gradual.

Significant Differences
The result of face-down grading is the fact that several diamonds of same-grade can appear different colors when viewed face-up. This can be influenced by several factors, including the following:

Laboratory Standards: Different laboratories have slightly different standards for color. Please see the page on Grading Laboratories for more information.

Shape: Brilliant cutting styles return light to the viewer more efficiently than step cuts, so a round brilliant may show less apparent colour face-up than an emerald or Asscher of the same grade.

Fluorescence: A diamond in the near-colorless or faint yellow range may have it’s face-up colour reduced by medium or stronger blue-fluorescence. This is only seen on a case-by-case basis.

Cut-Quality: A diamond cut with the critical angles and precision needed for highest performance have shorter ray-paths reducing their face-up colour; in some cases by multiple grades.

Color and cutting are related.
The finest cut round brilliants often face up with less color than the laboratory colour grade they were assigned, which was determined face-down. Why? Because light gets in and out of the diamond faster, on shorter ray-paths. This is the opposite with poor cutting, where critical angles are missed and light rays either escape through the pavilion or make multiple bounces before leaving, illuminating body tone. Poorly cut stones can face up noticeably darker.

Clarity

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Nearly all diamonds have natural characteristics that formed within the rough crystal over millions of years of growth. Most are microscopic and need magnification to detect. Others may be visible to the naked eye.

Absolutely Unique

What is certain is that no two diamonds are the same. Each is like a snowflake; never repeated in nature. In fact, one sure way to identify your diamond is to learn where a primary inclusion lies. Depending on the diamond’s clarity specifics – and your eyesight – it may be possible with no aid, or it may require a magnifying device. Either way, every diamond’s inclusions tell a special story that is absolutely unique.

Blemishes and Inclusions

Clarity characteristics are separated into two broad categories: Blemishes, which are external, and Inclusions, which are internal. The laboratory grading report will list all characteristics, in order of importance, with the primary characteristic(s) “setting” the clarity grade.

 Clarity

The Cut, Color, Clarity, Carat system emphasises clarity grade. This is determined by examining the diamond face-up at 10X magnification in neutral lighting. Five factors are considered: These include the size, number, position, visibility and type of characteristics visible at 10X magnification. If the implications are minute or minor the clarity grade is likely to be high. If the implications are noticeable or obvious the clarity grade will be lower.

  • When strictly graded, FL and IF indicate the diamond is Flawless, or Internally Flawless; revealing no inclusions at this magnification.
  • VVS1 and VVS2 indicate Very Very Slight inclusions; meaning that only minute characteristics were detected.
  • VS1 and VS2 imply Very Slight inclusions; the grader saw only minor characteristics.
  • SI1 and SI2 grades indicate the diamond was Slightly Included; inclusions were notable under 10X magnification.
  • I1 means Included; characteristics were obvious to the grader when magnified
  • .The I2 and I3 grades are reserved for diamonds with extremely obvious inclusions and/or durability issues caused by the inclusion type.

Naked-Eye Appearance

While diamonds are graded under 10X magnification they are not graded outside the ‘scope. This means that several diamonds of same-grade can appear differently to the naked eye. This is further influenced by several factors, including the following:
Laboratory Standards: Different laboratories have slightly different standards for clarity.
Shape: Brilliant cutting styles have greater faceting complexity and less transparency, so a round brilliant may show inclusions less than an emerald or Asscher of the same grade.
Size and Number:An inclusion plot that looks “clean” may not correspond to a cleaner presentation, since a single grade-setting crystal may be more naked-eye visible than several smaller crystals which set the same clarity grade collectively.

Position and Visibility: A diamond with a dark central inclusion can present with far more naked-eye visibility than one with a transparent inclusion under a girdle facet, yet both diamonds might have the same clarity grade.
Cut-Quality: A diamond cut with the critical angles and precision needed for highest performance boast superior brightness and scintillation, even when removed from jewelry store lighting, which helps to “mask” inclusions.
Cut quality affects visible clarity

A skilled diamond cutter can plan the “lay” of a grade-setting inclusion to reduce its face-up visibility. It may be impossible to omit a primary characteristic (and the resulting clarity grade) but a skilled cutter can orient the rough so that they become transparent or less visible. This is particularly true for SI1, SI2 and I1 clarity grades.

Carat Weight and Laboratory Grading

Carat weight is standardized and repeatable around the world. What is not repeatable is the assessment of whether a diamond is too shallow or deep to promote optimum light return.

 

Carat Weight

mettler-toledo-carat-scale-300x300

Diamond weight is expressed in carats. Carats are further divided into 100 “points” so that a 0.90 ct diamond may be called a 90-pointer, a 0.88 carat diamond an 88-pointer and so on. The word ‘carat’ has roots in ancient times, when diamonds were compared against carob beans by traders in the Ottoman Empire.

Buyer Beware

Carat weight is NOT size. Diamonds with the same carat weight can have smaller or larger vertical spreads, depending on the geometry of their cut. This is no different than two people weighing the same, but one is taller and the other is wider.

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Shallow and Deep Diamonds

Carat weight influences price more than any other factor so the goal of mass-manufacturers of diamonds will always be keeping as much weight from the rough crystal in the diamond as possible. This is even more important than the beauty of the final product since bigger diamonds bring bigger money. The result is millions of diamonds on the market which sparkle under bright lights (all diamonds do) but have average performance in normal lighting.

Fine Make Diamonds

Diamonds cut with a goal of beauty and high performance are proportionate, with critical angles and precision-cutting that will promote the best brightness, dispersion and scintillation, even in normal and romantic lighting. Such high performing diamonds appear larger than diamonds of normal cut quality because they have edge-to-edge brightness, not just a bright center. Because it costs more to fine-tune the rough to this degree of beauty, these diamonds are far more rare than shallow and deep diamonds and cost a bit more.

carat-weight

The example above, with a spread of 6.30 millimetres was cut slightly “deep” and will look smaller than a proportionate one-ct diamond, spreading closer to 6.50 mm. The example on the left above has greater spread, but was cut “shallow” and will lack the critical angles necessary for performance, reducing edge-to-edge brightness and potentially increasing dark zones.

 

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