When exploring Clarity Grading, it’s important to begin with a general understanding of the 4Cs. Until the mid-20th century, there was no standard approach to assessing the quality of diamonds. This changed in 1953, when the GIA (Gemological Institute of America) devised the 4Cs grading system, based on the diamond’s Cut, Color, Clarity and Carat weight. The 4Cs concept rapidly gained momentum and became the internationally accepted grading standard of the diamond industry. Let’s take a closer look at the 4Cs:
Carat is a weight unit used to measure diamonds and gemstones. It was formally adopted in 1907 at the Fourth General Conference on Weights & Measures in France, and soon spread across the globe as the internationally recognized standard.
Carat weight is a unit of mass equivalent to 0.2 grams. So, a 1 carat diamond is equivalent to 0.2 grams (200 milligrams). Smaller diamonds are often measured in carat points. There are 100 points in every carat. A 10-point diamond weighs one-tenth of a carat, or 0.02 grams. As a general rule, larger diamonds are more expensive than smaller diamonds. However, diamond pricing is affected by all 4Cs, so a smaller diamond of higher clarity and color, or a small superbly cut diamond may be priced higher than a larger, lesser quality diamond.
In their natural state, mined diamonds are rough and unpolished. Over hundreds of years, diamond cutting has evolved as both a science and art, using precise techniques and cut styles to maximize the beauty and value of the polished diamond.
The most common cut, appreciated for its classic appeal and ideal proportions, is the round brilliant. It features the traditional ‘table’ top, widening to the crown (top half), and then narrowing gradually below to form the pavilion (bottom half), all the way to the point tip, known as the culet.
Diamond cut is graded on a scale ranging from Excellent to Poor. Cut grade is determined by the diamond’s proportions and symmetry, which directly affect the way the diamond returns light to the viewer. For example, a pavilion that is cut too shallow or too deep will not make optimal use of light, reducing the diamond’s brilliance, and will therefore have a lesser grade.
During the long formation process deep in the earth, the diamond develops a natural hue. In its most perfect and prized form, a diamond is colorless and pure. However, this is rare. Most diamonds develop a tinge, whether slight or more obvious to the eye, as a result of the diamond’s chemical make-up or defects to the structure of the crystal lattice.
Over the past 100 years of diamond trading, diamonds have traditionally been sorted according to Color. The Color grading spectrum ranges from Colorless, which presents as a transparent bright white, through to Dark Yellow, the lowest Color grading.
However beautiful to the naked eye, most diamonds develop internal flaws and external blemishes during the natural formation process. Internal flaws, known as inclusions, may occur due to structural imperfections or the presence of crystals from foreign materials, causing a cloudy or milky appearance. External blemishes include cracks, chips, scratches, nicks and ‘naturals’, the term given to flaws on the original rough stone that were not polished by the diamond cutter.
Most inclusions and blemishes are very tiny, not visible to the naked eye. Yet whether internal or external, even tiny inclusions and blemishes can disrupt the travel of light as it enters and exits the diamond, affecting the clarity appearance of the diamond in significant ways.
The Clarity standard, used in the international diamond industry, presents a grading spectrum ranging from 0 Flawless (FL) to 10 Included (I3). Diamonds at the Flawless end of the spectrum are highly desirable and more expensive.
Clarity Grading Using a Technological Approach
Clarity grading has traditionally been determined by a diamond specialist who examines the diamond through a loupe (jeweler’s magnifying glass), and grades the diamond by comparing it to the standard Clarity grading scale.
With the advent of technologies in every part of life, it is no surprise that technologies are also a part of diamond grading. In fact, Cut grading was revolutionized in 1992, with the introduction of DiaMension™ to the market. It was the first software in the world to provide automated and computerized measurement of the diamond’s proportions – the most critical aspect affecting Cut grade. DiaMension™ changed the way that polished diamonds are assigned their Cut grade, enabling levels of accuracy never before seen or achieved. Today, almost every gem lab in the world uses DiaMension™ technology to derive the Cut grade of polished diamonds.
Recently, a new technology was announced that may well bring the same revolutionary changes to Clarity grading as DiaMension™ did to Cut grading. Sarine Clarity™ provides automated, objective Clarity measurement and grading. Based on comprehensive computerized mapping of the diamond’s inclusions and blemishes, Sarine Clarity™ provides grading capability that is non-biased and accurate.
In developing this technology, research included intensive studies of assorted polished diamonds by a team of gemologists, followed by a much larger sample size of diamonds to obtain deeper information about clarity measurement. When results proved to be inconsistent, due to the subjectivity and human limitations of grading diamond clarity, the research developed into the next stage with a much larger pool of gemologists and graders.
After years of trials and examinations, a buildup for a clarity grading algorithm was finally underway, and along with a wide assembly of new data, a dependable clarity grading system could be constructed. Wholly computerized, the clarity grading process need no longer be vulnerable to subjective, human perception. The Sarine Clarity™ system has also been developed with the capability to sort the diamonds into sub-categories according to pre-defined criteria, so each diamond can be targeted to its ideal sales market.
Clarity grading, enhanced by technology, and used in conjunction with the experience and expertise of the skilled gemologist, may well be on its way to a new generation of accuracy and reliability.