Diamond Grading systems by other organizations
The clarity grading system developed by the GIA has been used throughout the industry as well as by other diamond grading agencies including the American Gemological Society (AGS), European Gemological Laboratory (EGL), and the International Gemological Laboratory (IGL). These grading agencies base their clarity grades on the characteristics of inclusions visible to a trained professional when a diamond is viewed from above under 10x magnification.
The clarity grading system developed by the GIA has been used throughout the industry as well as by other diamond grading agencies including the American Gemological Society (AGS), European Gemological Laboratory (EGL), and the International Gemological Laboratory (IGL). These grading agencies base their clarity grades on the characteristics of inclusions visible to a trained professional when a diamond is viewed from above under 10x magnification.
Confédération Internationale de la Bijouterie, Joaillerie, Orfèvrerie des Diamants, Perles et Pierres (CIBJO).
The CIBJO or the International Confederation of Jewellery, Silverware, Diamonds and Stones developed the International Clarity Scale for grading diamonds. This clarity scale mirrors the GIA grading scale, except nomenclature varies. The CIBJO system names these clarity grades; Loupe Clean, Very, very small inclusions (VVS1 and VVS2), Very small inclusions (VS1 and VS2), Small inclusions (SI1 and SI2), Pique (P1, P2, and P3).
Clarity grading by CIBJO standards is by examination using a 10x achromatic, aplanatic loupe in normal light.
Clarity grading by CIBJO standards is by examination using a 10x achromatic, aplanatic loupe in normal light.
The IDC or the International Diamond Council uses a very similar standard to CIBJO. IDC loupe clean stones that have external blemishes have notations made on the grading report. IDC clarity grading is by examination using a 10x achromatic, aplanatic loupe in normal light.
The European Gemological Laboratory (EGL) introduced the SI3 as a clarity grade. While intended as a range to include borderline SI2 / I1 stones, it is now commonly used to mean I1's which are "eye clean", that is, which have inclusions which are not obviously visible to the naked eye.
Clarity grading considerations
All grades reflect the appearance to an experienced grader when viewed from above at 10x magnification, though higher magnifications and viewing from other angles are used during the grading process. The grader studies the diamond for internal characteristics, and judges them on the basis of five clarity factors; size, number, position, nature, and color or relief. The clarity grade is assessed on the basis of the most noticeable inclusions, otherwise called: grade setting inclusions. This means that less significant inclusions are ignored for the purposes of setting the grade. However, they may still be plotted onto a diamond plot chart. -Wikipedia.org-
Clarity grading considerations
All grades reflect the appearance to an experienced grader when viewed from above at 10x magnification, though higher magnifications and viewing from other angles are used during the grading process. The grader studies the diamond for internal characteristics, and judges them on the basis of five clarity factors; size, number, position, nature, and color or relief. The clarity grade is assessed on the basis of the most noticeable inclusions, otherwise called: grade setting inclusions. This means that less significant inclusions are ignored for the purposes of setting the grade. However, they may still be plotted onto a diamond plot chart. -Wikipedia.org-
Accurate clarity grading as with other grading steps must be done with the diamond loose; meaning not set into any mounting. Inclusions are often difficult to see from the crown side of the diamond, and may be concealed by the setting.
Size
The first clarity factor which is assessed is a clarity characteristic's size. Larger characteristics are typically more noticeable under magnification, thereby placing the diamond into a lower clarity grade.
Number
The second clarity factor which is assessed is the number of clarity characteristics. Generally the more characteristics the lower the clarity grade. This assessment is made by judging how readily they can be seen, not by the actual number of characteristics.
Position
The third clarity factor which is assessed is the characteristic's position. When an inclusion is directly under the table of the diamond it is most visible. An inclusion under the table and positioned close to a pavilion facet, will reflect multiple times around the stone, giving this type of inclusion the name reflector. Reflectors are graded as if each reflection were an inclusion (although in plotting the diamond it is only plotted once). For this reason reflectors have a greater impact on the clarity grade. Inclusions become less visible when they are positioned under the crown facets, or near the girdle of the stone. These inclusions may often be more easily seen from the pavilion side of the diamond than from crown side of the diamond.
In addition the position of large feathers, knots and included crystals positioned where they extend to the girdle or crown of the stone, affect the clarity grade. Diamonds worn in jewelry typically will withstand breakage, however inclusions of this nature, in these positions, can pose a risk for further extension of the break in the structure of the diamond. Inclusions that are judged to pose at least a moderate risk of breakage to the stone are graded in the included category.
Nature
The fourth clarity factor which is assessed is a characteristic's nature. The characteristic's nature determines whether it is internal where they extend into the stone, or external; where they are limited to the surface of the stone. Internal characteristics automatically exclude the diamond from the flawless, and internally flawless categories. External characteristics exclude the diamond from the flawless category.
A diamond's internal characteristics can be a; bruise, cavity, chip, cleavage, cloud, crystal, feather, grain center, indented natural, internal graining, knot, laser drill hole, needle, pinpoint, or twinning wisp.
A diamond's external characteristics can be an; abrasion, natural, nick, pit, polish lines, polish mark, scratch, surface graining, or extra facet.
The nature will also detail whether an inclusion poses a risk to the stone. Inclusions that cause or may cause a break in the crystal structure (included crystal, feather, knot, cleavage) are considered alongside their position, to assess whether they pose a moderate level of risk for further breakage.
Color or relief
The fifth clarity factor which is assessed is the color and relief of clarity characteristics. Characteristics that contrast with the surrounding diamond are said to have relief. The degree to which this color and relief is noticeable affects the clarity grade of the diamond. Colored inclusions invariably show contrast and are more easily seen. An exception is a black pinpoint inclusion which is often more difficult to see than a white pinpoint.
The second clarity factor which is assessed is the number of clarity characteristics. Generally the more characteristics the lower the clarity grade. This assessment is made by judging how readily they can be seen, not by the actual number of characteristics.
Position
The third clarity factor which is assessed is the characteristic's position. When an inclusion is directly under the table of the diamond it is most visible. An inclusion under the table and positioned close to a pavilion facet, will reflect multiple times around the stone, giving this type of inclusion the name reflector. Reflectors are graded as if each reflection were an inclusion (although in plotting the diamond it is only plotted once). For this reason reflectors have a greater impact on the clarity grade. Inclusions become less visible when they are positioned under the crown facets, or near the girdle of the stone. These inclusions may often be more easily seen from the pavilion side of the diamond than from crown side of the diamond.
In addition the position of large feathers, knots and included crystals positioned where they extend to the girdle or crown of the stone, affect the clarity grade. Diamonds worn in jewelry typically will withstand breakage, however inclusions of this nature, in these positions, can pose a risk for further extension of the break in the structure of the diamond. Inclusions that are judged to pose at least a moderate risk of breakage to the stone are graded in the included category.
Nature
The fourth clarity factor which is assessed is a characteristic's nature. The characteristic's nature determines whether it is internal where they extend into the stone, or external; where they are limited to the surface of the stone. Internal characteristics automatically exclude the diamond from the flawless, and internally flawless categories. External characteristics exclude the diamond from the flawless category.
A diamond's internal characteristics can be a; bruise, cavity, chip, cleavage, cloud, crystal, feather, grain center, indented natural, internal graining, knot, laser drill hole, needle, pinpoint, or twinning wisp.
A diamond's external characteristics can be an; abrasion, natural, nick, pit, polish lines, polish mark, scratch, surface graining, or extra facet.
The nature will also detail whether an inclusion poses a risk to the stone. Inclusions that cause or may cause a break in the crystal structure (included crystal, feather, knot, cleavage) are considered alongside their position, to assess whether they pose a moderate level of risk for further breakage.
Color or relief
The fifth clarity factor which is assessed is the color and relief of clarity characteristics. Characteristics that contrast with the surrounding diamond are said to have relief. The degree to which this color and relief is noticeable affects the clarity grade of the diamond. Colored inclusions invariably show contrast and are more easily seen. An exception is a black pinpoint inclusion which is often more difficult to see than a white pinpoint.
