Diamonds: The 4 C’s

Color: The First C

Except for very rare and fancy colors, a diamond is more valuable when it has less color.

Although many diamonds appear to have no color at all, trace atomic elements other than carbon (C) may result in slight degrees of yellow, brown, or gray body coloring. These colors can seriously affect the overall value of your stone. The color grade of a diamond is the amount of color the diamond has when viewed table-down, from its side, against a neutral white background under specific lighting conditions. The color differences are often so slight that they are only detected by comparing them against a master set of laboratory-graded diamonds.

As a rule, color differences are measured by international grading scales created by either the American Gemological Society (AGS) or the Gemological Institute of America (GIA).

As shown in the Diamond Color Chart, the color scale begins at D. As a diamond’s color increases, the corresponding letter grade on the chart moves away from D toward the letter Z. To put this in perspective, almost 85% of the world’s production of diamonds falls below the “M” color. Diamonds graded D, E and F are considered “colorless” and are the rarest stones. Diamonds that measure G, H, I and frequently J colors are considered “near-colorless”. Diamonds graded K and below generally are used to make inexpensive pieces for big-box, chain and online retailers or for industrial applications.

While many jewelers will carry diamonds graded a J and below, Crescent Jewelers believes that your diamond should show no visible color and will only sell these diamonds to customers who are willing to sacrifice color for price. When selecting your diamond, ask your trained salesperson to help you compare the color of the diamonds when you are selecting your stone.

As mentioned, generally colorless diamonds are more valuable, however diamonds with naturally-occurring “fancy” colors may be an exception. These diamonds may be pink, blue, green and fancy yellow (also called canary yellow) as well as other colors. These diamonds are not graded on the traditional color chart.

Natural occurring fancy colors can be even more rare than colorless diamonds. However, they frequently contain different hues and saturation causing inconsistency in color. As a result, many manufacturers will irradiate colored or colorless stones using a stream of electrons to alter the crystallographic structure of the diamond. This produces permanent change in the color of the diamond to create a fancy diamond. Because irradiated diamonds are not rare, they are much less valuable than naturally-occurring gemstones.

Clarity: The Second C

Millions of years ago, when diamonds were forming as crystals of pure carbon in the Earth’s mantle, minute traces of other minerals or gas were sometimes trapped inside the matrix. These inclusions may appear as tiny specks, lines, feathers or clouds inside a diamond. They are nature’s fingerprints. Clarity is the evaluation of these characteristics, both internally and externally.

Fewer and less visible fingerprints make a diamond more valuable. Inclusions are inside the diamond; two of the most common inclusions are:

  • Crystals: Merely minerals trapped inside the diamond
  • Feathers: Breaks in the diamond

Another type of inclusion is called a blemish. Blemishes are usually very small and are only on the surface of diamonds.

Diamonds are graded under a 10X loupe and the grade reflects the number, size, and placement of the inclusions and blemishes. Crescent Jewelers uses as standard equipment binocular stereo microscopes which are able to zoom to higher magnifications to map out these imperfections in the diamonds and grade our diamonds. These microscopes are equipped with darkfield illumination, as well as an ultraviolet light filtered overhead light. When buying a diamond, you should ask your trained salesperson to show you the inclusions in each stone.

While these inclusions are imperfections in a stone, they are features—like a fingerprint—that makes each diamond unique. Crescent Jewelers sells diamonds graded between Flawless (FL) and Slightly Included (SI1 & SI2). We do not sell engagement diamonds below SI2 except at the specific request of each customer.

The Gemological Institute of America (GIA) Diamond Grading Scale is divided into eleven grades and six broader categories, each graded under 10x magnification. 

Clarity Enhancements

Recently, technology has allowed manufacturers to “enhance “the clarity of a diamond. These enhancements generally involve laser-drilling out an existing inclusion that was once visible to the unaided eye and filling the inclusion with clear substance-a process called fracture filling. The way to detect “fracture filled” or “clarity enhanced” diamonds is under the scope. The filling generally leaves a faint or strong neon color in the stone, which when observed face up is either invisible or could easily be mistaken for the spectral colors that are observed when looking at a stone face up. When the diamond is observed face down under a scope however the neon colors distinctly stand out. A buyer should not pay more for clarity-enhanced diamonds than they would for the diamond prior to the treatment. Heating the stone can result in the filling draining out of the stone and the inclusion re-appearing. Crescent Jewelers does not sell clarity enhanced diamonds.

Clarity Grading Scale (10x Magnification)

F / Flawless Diamond

F / Flawless Diamond

The diamond shows no inclusions or blemishes of any sort under 10X magnification when observed by an experienced grader. Note: Truly flawless or internally flawless (F or IF on the GIA’s grading scale) diamonds are extremely rare.
IF / Internally Flawless Diamond

IF / Internally Flawless Diamond

The diamond has no inclusions when examined by an experienced grader using 10X magnification, but will have some minor blemishes.
VVS1, VVS2 / Very, Very Slightly Included Diamond

VVS1, VVS2 / Very, Very Slightly Included Diamond

The diamond contains minute inclusions that are difficult even for experienced graders to see under 10X magnification. VVS1 is a higher clarity grade than VVS2.
VS1, VS2 / Very Slightly Included Diamond

VS1, VS2 / Very Slightly Included Diamond

The diamond contains minute inclusions such as small crystals, clouds or feathers when observed with effort under 10X magnification. VS1 is a higher clarity grade than VS2. Typically the inclusions in VS diamonds are invisible without magnification, however infrequently some VS2 inclusions may still be visible to the eye.
SI1, SI2 / Slightly Included Diamond

SI1, SI2 / Slightly Included Diamond

The diamond contains inclusions (clouds, included crystals, knots, cavities, and feathers) that are noticeable to an experienced grader under 10X magnification. In 1992 the European Gem Laboratory (EGL) introduced another grade of clarity: SI3. GIA did not recognize this new grade.
I1, I2, I3 / Included Diamond

I1, I2, I3 / Included Diamond

The diamond contains inclusions (possibly large feathers or large included crystals) that are obvious under 10X magnification and may affect transparency and brilliance. Inclusions in I1 diamonds often are seen to the unaided eye. I2 inclusions are easily seen, while I3 diamonds have large and extremely easy to see inclusions that typically impact the brilliance of the diamond, as well as having inclusions that are often likely to threaten the structure of the diamond.

Carat Weight: The Third C

Carat weight is probably the most familiar term when it comes to buying a diamond. A carat is a unit of weight for diamonds. Diamonds under one carat are often discussed in terms of “points” — each point representing 1/100th of a carat. For example, a 50 point diamond is one half of a carat.

It is important to know that a one-carat diamond is much more rare and more expensive than a group of several smaller diamonds, which combined add up to one carat in total weight (with all other factors equal).

Carat weight is the easiest factor of the 4C’s to gauge accurately and is the most objective. All that is required is a delicately balanced scale capable of weighting extremely small weights. Yet, despite the ease of measurement and the relative unimportance of diamond weight, there are some facts you should understand about weight and price.

As diamonds increase in size, their cost tends to increase geometrically rather than arithmetically. As a result, a one-carat diamond may cost more than twice as much as a one-half carat stone of equal quality.

Further, weight does not always enhance the value of a diamond. In fact, when a stone is improperly cut, added weight may serve only to reduce its brilliance.

Cut: The Fourth C

For the purposes of determining value of a diamond, the “cut” of the diamond refers to the quality of the craftsmanship, including the proportions, polish, and symmetry of the diamond. While color, clarity and carat weight help determine a diamond’s rarity, it is the cut of a diamond that defines its true beauty. Cut determines how well a diamond will reflect and refract light. The more precisely a diamond is proportioned and polished, the bigger it will look and the more brilliantly it will perform.

Many people confuse cut with the shape of a diamond. The shape you select is a matter of individual taste, and today your choice is only limited by the skill and imagination of the craftsman.

The cutting grade is determined by the diamond cutter’s effort to maximize the refraction of light during every stage of the fashioning process. Most brilliant-cut or fancy-shaped diamonds possess fifty-eight carefully angled facets whose placement will affect the fire, brilliance and ultimate beauty of each diamond.

The cut is the most critical component of the 4C’s because the quality of the cut determines how much fire, brilliance and beauty each diamond possesses. As a result, the value of two diamonds with exactly the same carat weight could vary by up to 50% depending on the quality of cut. Unfortunately, unlike carat weight, color and clarity, cut is the most difficult to label or quantify. The elements of the “cut” of the diamond are proportion, polish, and symmetry.

Cut: The Importance of Proportion, Polish, & Symmetry

The most commonly understood element of “cut” is the proportions of the stone. A well proportioned diamond allows light to enter the table facet, travel through the pavilion where it will be reflected from one side to another, then reflect back out through the table facet. A poorly proportioned diamond will allow the light to “leak” out from the sides or bottom of the pavilion rather than reflect back out the top facet. More brilliance and fire are created when a diamond reflects more light.

The full realization of the potential of a diamond’s brilliance, dispersion and scintillation and getting the proper balance between these three elements is achieved mainly through proper cut proportions. The important proportions are:

  1. Table size
  2. Crown height and angle (angle of the bezel facets with the girdle)
  3. Pavilion depth and angle (angle of the pavilion facets with the girdle)
  4. Girdle thickness
  5. Culet size

If a brilliant diamond (for example a round, princess cut, heart, radiant, and the Dream® by Hearts On Fire®) is cut too deep or too shallow light leaks out of the pavilion and does not return to the observer’s eye. In diamonds with too steep a crown angle, exiting light is directed out to the side where it isn’t visible, or it can be reflected back into the stone. In diamonds with large tables, if the crown angle is too shallow there is little visible dispersion of light. Round brilliant cut diamonds with ideal proportions will reflect the most amount of light and are, therefore, referred to as “ideal”.

Currently there is no widely accepted “ideal” range of proportions for the fancy shaped diamonds-although the Dream® diamond by Hearts on Fire® is perfectly proportioned and precisely cut for maximum beauty, brightness, fire and sparkle. When looking at the general appearance of fancy cut diamonds, make sure that the stone is appealing to your eye and that it is bilaterally symmetrical.


Also look at the shape of the pavilion, especially on emerald cuts, from all angles to make sure it isn’t too deep and doesn’t bulge excessively, an indication of extra weight retention and perhaps a reduction in light return (brilliance). In many fancy shaped diamonds (marquise, pear, oval, emerald, and heart shapes) the pavilion facets do not culminate at a point at the tip of the pavilion, but rather form an edge. However, for grading purposes this is still referred to as the culet and should be judged accordingly.

While the proportions of the diamond could be perfect in all regards, with all of the angles properly cut, the facets cut and angled properly, and the depth/table percentage perfect. However, even with all of that being correct, if the polish or symmetry of the diamond is off, the diamond’s cut grade will suffer.


The polish of the diamond is essential to the cut grade in that it represents the ease of light to enter and exit the diamond. If the polish of the diamond is poor, the play of light emanating from the diamond’s crystalline structure will neither receive the light it requires in order to produce its full effect, nor return the light to the eye with the color spectrum fully in tact. In short, the polish of the outer facets of the diamond is just as important to the cut grade as the diamond’s proportions.


The symmetry of the diamond is just as important as the polish in formulating the final cut grade. The symmetry refers to the placement of the facets on the diamond’s face. Even should all other aspects of the diamond be absolutely excellent, a poor placement of the diamond’s facets, or the poor angling and sizing of the facets, can ruin a diamond’s cut grading. It is extremely important to the diamond’s light effect to have each and every facet evenly placed, sized according to the particular needs of the cut, and angled at the proper degrees.

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