Understand the 4Cs of Diamond Quality – Colour, Clarity, Cut, Carat
This basic knowledge will not only unlock the mystery of a diamond’s quality, it will also help you understand a diamond’s value and price.
Diamond Color Actually Means Lack of Color
In most diamonds, the term actually refers to the absence of diamond color. The less color in the stone, the more desirable and valuable it is. Some of these differences are not visible to the naked eye, but directly impact the overall quality and price of the stone.
The diamond color evaluation of most gem-quality diamonds is based on the absence of color. A chemically pure and structurally perfect diamond has no hue, like a drop of pure water, and consequently, a higher value. GIA’s D-to-Z diamond color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to masterstones of established color value.
Many of these diamond color distinctions are so subtle that they are invisible to the untrained eye; however, these distinctions make a very big difference in diamond quality and price.
Why does the color grading system start at D?
Before GIA universalized the D-to-Z Color Grading Scale, a variety of other systems were used loosely, from A, B, and C (used without clear definition), to Arabic (0, 1, 2, 3) and Roman (I, II, III) numbers, to descriptive terms like “gem blue” or “blue white,” which are notorious for misinterpretation. So the creators of the GIA Color Scale wanted to start fresh, without any association with earlier systems. Thus the GIA scale starts at the letter D. Very few people still cling to other grading systems, and no other system has the clarity and universal acceptance of the GIA scale.
Are diamonds graded as Zs considered fancy-color?
No. Naturally colored diamonds outside the normal color range are called fancy-color diamonds. The FTC provides no guidelines for the use of the term “fancy-color” in the US, but there is general agreement in the international trade that fancy-color diamonds are either yellow or brown diamonds that have more color than a Z masterstone or they exhibit a color other than yellow or brown.
Diamond Clarity Refers to the Absence of Inclusions and Blemishes
Diamond Clarity measures the amount, size and placement of internal ‘inclusions,’ and external ‘blemishes.’ Grades run from ‘Flawless,’ with virtually no imperfections, to ‘Included,’ which contain a significant number of imperfections.
Natural diamonds are the result of carbon exposed to tremendous heat and pressure deep in the earth. This process can result in a variety of internal characteristics called ‘inclusions’ and external characteristics called ‘blemishes.’
Evaluating diamond clarity involves determining the number, size, relief, nature, and position of these characteristics, as well as how these affect the overall appearance of the stone. While no diamond is perfectly pure, the closer it comes, the higher its value.
The GIA Diamond Clarity Scale has 6 categories, some of which are divided, for a total of 11 specific grades.
Many inclusions and blemishes are too tiny to be seen by anyone other than a trained diamond grader. To the naked eye, a VS1 and an SI2 diamond may look exactly the same, but these diamonds are quite different in terms of overall quality. This is why expert and accurate assessment of diamond clarity is extremely important.
How did the GIA clarity scale come to be?
Like the color scale, GIA’s clarity grading system developed because jewelers were using terms that could be misinterpreted, “loupe clean” or “piqué.” Today, even if you buy a diamond somewhere else in the world, the jeweler will most likely use terms like VVS1 or SI2, even if his or her language is French or Japanese instead of English.
What causes inclusions?
Small crystals can become trapped in a diamond when it’s forming. Sometimes as a crystal grows it can develop irregularities in its atomic structure.
A Diamond’s Cut Unleashes Its Light
Diamond Cut does not refer to a diamond’s shape, but to the proportion and arrangement of its facets and the quality of workmanship. The amount of brilliance, sparkle and fire in a diamond is determined by cut. Grades range from ‘Excellent’ to ‘Poor.’
Diamonds are renowned for their ability to transmit light and sparkle so intensely. We often think of a diamond’s cut as shape (round, heart, oval, marquise, pear), but a diamond’s cut grade is really about how well a diamond’s facets interact with light.
Precise artistry and workmanship are required to fashion a stone so its proportions, symmetry and polish deliver the magnificent return of light only possible in a diamond.
A diamond’s cut is crucial to the stone’s final beauty and value. And of all the diamond 4Cs, it is the most complex and technically difficult to analyze.
To determine the cut grade of the standard round brilliant diamond – the shape that dominates the majority of diamond jewelry – GIA calculates the proportions of those facets that influence the diamond’s face-up appearance. These proportions allow GIA to evaluate how successfully a diamond interacts with light to create desirable visual effects such as:
GIA’s diamond cut grade also takes into account the design and craftsmanship of the diamond, including its weight relative to its diameter, its girdle thickness (which affects its durability), the symmetry of its facet arrangement, and the quality of polish on those facets.
The GIA Diamond Cut Scale for standard round brilliant diamonds in the D-to-Z diamond color range contains 5 grades ranging from Excellent to Poor.
How does pavilion depth affect a diamond's cut?
The distance from the bottom of the girdle to the culet is the pavilion depth. A pavilion depth that’s too shallow or too deep will allow light to escape from the side of the stone or leak out of the bottom. A well-cut diamond will direct more light through the crown.
Diamond Carat Weight Measures a Diamond’s Apparent Size
Diamond images are for reference only and may vary based on screen size
Diamond Carat refers to a diamond’s weight. Generally speaking, the higher the carat weight, the more expensive the stone. Two diamonds of equal carat weight, however, can have very different quality and price when the other three Cs are considered.
No matter how beautiful a diamond may look you simply cannot see its true quality. The 4Cs of diamond quality will provide you with the information you need to know the diamond’s actual quality.
Diamond carat weight is the measurement of how much a diamond weighs. A metric “carat” is defined as 200 milligrams.
Each carat can be subdivided into 100 ‘points.’ This allows very precise measurements to the hundredth decimal place. A jeweler may describe the weight of a diamond below one carat by its ‘points’ alone. For instance, the jeweler may refer to a diamond that weighs 0.25 carats as a ‘twenty-five pointer.’ Diamond weights greater than one carat are expressed in carats and decimals. A 1.08 carat stone would be described as ‘one point oh eight carats.’
All else being equal, diamond price increases with diamond carat weight because larger diamonds are rarer and more desirable. But two diamonds of equal carat weight can have very different values (and prices) depending on three other factors of the diamond 4Cs: Clarity, Color, and Cut.
It’s important to remember that a diamond’s value is determined using all of the 4Cs, not just carat weight.
How did the carat system start?
The modern carat system started with the carob seed. Early gem traders used the small, uniform seeds as counterweights in their balance scales. The carat is the same gram weight in every corner of the world.
What are “MAGIC SIZES”? (define magic sizes too)
Some weights are considered “magic sizes” – half carat, three-quarter carat, and carat. Visually, there’s little difference between a 0.99 carat diamond and one that weighs a full carat. But the price differences between the two can be significant.
Diamond’s Reaction to Long Wave UV Rays
Fluorescence is the visible light some diamonds emit when they are exposed to invisible ultraviolet (UV) rays. On a GIA diamond grading report, fluorescence refers to the strength, or intensity, of the diamond’s reaction to long-wave UV, which is an essential component of daylight. The light emitted lasts as long as the diamond is exposed to the ultraviolet source.
Approximately 25% to 35% of the diamonds submitted to GIA over the past decade, exhibit some degree of fluorescence. However, only 10% of those show strengths of fluorescence that may impact appearance (i.e., strengths noted on laboratory reports as medium, strong or very strong). In more than 95% of the diamonds that exhibit fluorescence, the color seen is blue. In rare instances, the reaction is yellow, white or another color.
What impact does fluorescence have on the appearance of a diamond?
GIA studies show that, for the overwhelming majority of diamonds, the strength of fluorescence has no widely noticeable effect on appearance. In many instances, observers prefer the appearance of diamonds that have medium to strong fluorescence. In rare cases, some diamonds with extremely strong fluorescence may appear hazy or oily; less than 0.2% of the fluorescent diamonds submitted to GIA exhibit this effect.
Does fluorescence compromise the structural integrity of the diamond?
No. A diamond that fluoresces has the same integrity as one with no reaction to UV. Submicroscopic substitutions and/or shifts in the diamond structure can cause fluorescence as well as prevent it. Nothing in either instance inherently weakens or is bad for the diamond.
Diamonds are remarkably durable, resist scratching (except by other diamonds) and maintain their brilliance over time. But diamonds aren’t indestructible. They can be chipped by a sharp blow, become loose or lost in a weakened setting, or be damaged by contact with other diamonds. Wear diamond jewelry with care. Store it in padded boxes or soft bags separate from other jewelry. Clean your jewelry by wiping it with a lint-free cloth or with warm water, mild soap and a soft toothbrush, or by dipping it briefly in a commercial cleaning solution. Have your diamond jewelry periodically cleaned and its setting examined by a professional jeweler to maintain its beauty and integrity over time.
Changing the Natural Essence of the Diamond
While treatments can increase a stone’s Color or Clarity, the presence of such enhancements may affect the diamond’s value – particularly if the price reflects its appearance after treatment.
Color Enhancements
While many of these are not common in the market, GIA tests every diamond it grades for their presence.
Coating enhances a diamond’s color by masking an undesirable body color with an ultra-thin layer of chemicals or plastics. Another form of coating involves applying a thin film of synthetic diamond to the surface of a diamond simulant, giving it certain characteristics of a real diamond.
HPHT stands for a high-pressure, high-temperature. The process is an effective tool for changing the color of certain diamonds, making them colorless, pink, blue, green, yellowish green, or yellow. Outside of a well-equipped grading laboratory, this form of treatment is virtually undetectable.
The 6.61 ct diamond above shows the stone before and after HPHT annealing to remove its color. Left, prior to annealing, this diamond’s color was considered fancy yellow brown. Right, after annealing, this diamond’s color grade is “L” (faint yellow).
Clarity Enhancements
There are two main techniques for improving a diamond’s apparent clarity; laser drilling and fracture filling. Laser drilling is commonly used to remove small dark inclusions. The laser bores a small hole into the diamond’s interior and burns away the inclusion, or creates a channel through which a bleaching agent can be introduced to improve the inclusion’s appearance.
The geometry of the table, girdle, crown, and pavilion facets is what dictates the diamond’s brilliance and beauty, ensuring that it will catch the eye from every angle.
Hearts and Arrows diamond are unmatched in precision, beauty and perfection in cutting. Solitaire Club only chooses diamonds with clearly defined set of 8 Hearts and 8 Arrows.
The surface of a diamond is the threshold through which light enters the stone. Even relatively minor surface abrasions can interfere with the stone’s ability to properly interact with light.
Solitaire Club only selects diamond with excellent polish.
The angle between the bezel facets and the top of the girdle plane affects a diamond’s appearance. Generally, crown angle from 32 to 36 degrees produce attractive, bright, and fiery diamonds when combined with the right table percentage and pavilion angle.
The table is key to the diamond’s appearance as its size influences the amount of light that enters and exits a diamond. Solitaire Club only chooses diamonds with the table percentage ranging from 55% – 57% only. This is to ensure each diamond produces the most fire and greatest brilliancy.
The pavilion angle is crucial to the gem’s overall appearance. Even the slightest imbalance may tip the returning light from hitting the crown. This results in uneven brightness and scintillation, which makes the reflection patterns difficult to spot.
At Solitaire Club, we further tighten the requirement for crown angle, table percentage and pavilion depth and angle to ensure each and every diamond selected produces the best brilliance with its reflection and refraction.
