Basics of diamonds
This basic knowledge will not only unlock the mystery of a diamond’s quality, it will help you understand a diamond’s value and price.
Each diamond is unique and is a miracle of time, place and change. And each has specific qualities that establish its value.
Until the middle of the twentieth century, there was no agreed-upon standard by which diamonds could be judged. GIA created the first, and now globally accepted standard for describing diamonds: Color, Clarity, Cut and Carat Weight.
Today, the 4Cs of Diamond Quality is the universal method for assessing the quality of any diamond, anywhere in the world. The creation of the Diamond 4Cs meant two very important things: diamond quality could be communicated in a universal language, and diamond customers could now know exactly what they were about to purchase.
(a) Color :
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 master stones of established color value.
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.
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.
(b) Clarity :
Diamond clarity refers to the absence of Inclusions and blemishes.
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.
• Flawless (FL) : No inclusions and no blemishes visible under 10x magnification
• Internally Flawless (IF) : No inclusions visible under 10x magnification
• Very, Very Slightly Included (VVS1 and VVS2) : Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
• Very Slightly Included (VS1 and VS2) : Inclusions are observed with effort under 10x magnification, but can be characterized as minor
• Slightly Included (SI1 and SI2) : Inclusions are noticeable under 10x magnification
• Included (I1, I2, and I3) : Inclusions are obvious under 10x magnification which may affect transparency and brilliance.
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.
(c) Cut :
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:
• Brightness : Internal and external white light reflected from a diamond
• Fire : The scattering of white light into all the colors of the rainbow
• Scintillation : The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond
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 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. That’s why pavilion depth affect a diamond’s cut.
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.
(d) Carat Weight :
Diamond carat weight is the measurement of how much a diamond weighs. A metric “carat” is defined as 200 milligrams.
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.
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 more rare 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.
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.
Diamonds Fluorescence :
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.
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; fewer than 0.2% of the fluorescent diamonds submitted to GIA exhibit this effect.
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.
Diamond Insurance and appraisal :
Insuring high-value personal property is a good idea, and your diamonds and jewelry is no exception. Homeowner’s and renter’s insurance policies usually offer coverage for diamonds and jewelry theft, but not necessarily damage or loss. Carefully review your policy. Depending on the value of your collection, you might consider insurance specifically for your diamonds and jewelry. Ask whether this policy would cover unset diamonds, gemstones and antique jewelry.
An appraisal is important for insurance purposes as well as for future upgrades or possible resale. While GIA can’t recommend an individual appraiser, there are several appraisal associations and networks that can help you locate one in your area. These are national associations that have members all over the country, and many require that their appraisers have a GIA Graduate Gemologist (GG) diploma from GIA in addition to supplemental appraisal training.
Care your diamonds :
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.