Clarity is one of the four Cs of grading diamonds, along with cut, color, and carat. Diamond clarity determines the stone's value by assessing tiny flaws within the stone and slight imperfections on its surface. Most such flaws are invisible to the naked eye and rarely affect the beauty of the stone. For this reason, gemologists often refer to them as internal characteristics rather than flaws. Minor internal and surface imperfections can be useful for identifying diamonds, as gemologists and jewelers use them to differentiate natural stones from synthetic.
Differentiating Between Inclusions and Blemishes
Inclusions are the internal characteristics of a diamond that are visible under magnification. These can be gases, solids, or liquids trapped within the structure of the stone. They can also be tiny cracks, smaller pieces of diamonds, or other foreign materials. Inclusions make each diamond unique and give it a signature look. Gemologists classify the most common internal characteristics found in diamonds as feathers, clouds, crystals, cavities, cleavage, knots, graining, and laser lines.
Blemish is the term used to describe a surface defect on a piece of diamond. Common blemishes include chips, pits, nicks, scratches, breaks, abrasions, grain lines, polish lines, and light and dark spots. The numbers, locations, and sizes of inclusions and blemishes on a diamond determine its overall clarity. These flaws affect the stone's brilliance as they interfere with light as it passes through the diamond's crystalline structure.
Understanding the GIA Diamond Clarity Grading System
The Gemological Institute of America (GIA) established a diamond grading system with a clarity scale in 1953. Their scale examines clarity characteristics and determines diamond grades viewed under 10x magnification. The diamond clarity scale has the following six categories and 11 grades:
- Flawless (FL) — no inclusions or blemishes. Such stones are rare, accounting for less than 1% of all diamonds.
- Internally Flawless (IF) — no inclusions but possess small blemishes.
- Very, Very Slightly Included (VVS1 and VVS2) — minute inclusions that a trained eye will find difficult to see under 10x loupe. Also known as eye-clean diamonds, these have minuscule internal characteristics appearing as needles and pinpoints. VVS1 diamonds have higher clarity than VVS2 stones.
- Very Slightly Included (VS1 and VS2) — also have tiny inclusions. While these are difficult to see in VS1 stones under 10x magnification, they are somewhat easy to find in VS2 diamonds. In some VS2 stones, the inclusions are visible to the naked eye under ideal conditions.
- Slightly Included (SI1 and SI2) — have noticeable inclusions at 10x magnification. SI1 stones, in this category, have higher clarity than SI2 ones.
- Included (I1, I2, and I3) — clearly visible inclusions often seen by the unaided eye in I1 stones and easily seen in I2 diamonds. Inclusions in I3 diamonds are large and easy to see. They may affect the brilliance of the stone and reduce its resistance to fracture.
Determining a Diamond Clarity Grade
When grading a diamond for clarity, the expert views the stone from above and at 10x magnification. It's possible that the grader uses higher magnifications and views the diamond from other angles to determine whether an inclusion is truly present or not. When grading diamonds, gemologists examine them loose—they are removed from their jewelry setting. This is because settings can block inclusions, and these internal characteristics are difficult to spot when viewing diamonds from their crowns. Before assigning a diamond clarity grade, an experienced gemologist examines the number, size, nature, position, and color of the inclusions they find.
The size of an inclusion affects the final clarity grade because more prominent inclusions are easier to spot under magnification. The number also affects the overall grade because more inclusions reduce the overall brilliance of the stone. Similarly, internal characteristics located under the table are more visible than those under the crown facets and near the girdle of the diamond. Those close to the pavilion facets of a stone lower the clarity grade further because they have multiple reflections in the diamond's crystalline structure. Inclusions positioned where they increase the chances of breakage lower a diamond's clarity grade.
The type or nature of a diamond flaw also influences its final grade. Both internal and external clarity characteristics affect the grade assigned by a gemologist. A blemish excludes a diamond from an FL grade (flawless), while an inclusion excludes it from FL and IF categories. A colored inclusion is more visible than a colorless one because it contrasts sharply with its surroundings. The degree of relief created by this contrast affects the diamond's final clarity grade.
Diamond Clarity FAQs
Are there other diamond clarity grading systems?
Yes. The most prominent is the International Clarity Scale developed by the World Jewellery Confederation, also known as CIBJO. Compared to the GIA grading system, it substitutes Loupe Clean for FL and IF grades, names the I grades as Pique (P1, P2, and P3), and keeps the VVS, VS, and SI grades but uses the term Small Inclusions rather than Slightly Included.
Others include systems developed by the American Gem Society (AGS), International Diamond Council (IDC), and the European Gemological Laboratory (EGL). The AGS uses a number scale that goes from 0 to 10. This correlates with the GIA scale, but with IF and FL, grades assigned a 0. The IDC scale is the same as the CIBJO scale, but it assigns the loupe clean grade to stones with some blemishes. The EGL scale is similar to the GIA scale but with an expanded SI rating that includes an SI3 grade for borderline SI2/I1 stones.
Which diamond clarity grades offer the best value?
VS and SI diamonds offer the best value. These have invisible to barely visible inclusions to the naked eye or hidden under settings when used as engagement ring gemstones and other jewelry items. They are also not as expensive as the rare stones in FL, IF, and VVS grades.
Does stone size and shape affect diamond clarity?
Yes. A bigger diamond has larger facets that can reflect and magnify inclusions more easily than smaller ones. When looking for a diamond over one carat in size, find one with the highest clarity grade available that you can afford. Similarly, certain diamond shapes make flaws more visible. Emerald and Asscher cuts fall in this category. The rectangular facets of emerald-shaped and step-cut diamonds enhance transparency and make it easier to see farther into the stones.