Diamonds Prices Details
IA clarity grading is performed under 10x magnification with darkfield illumination. The GIA Laboratory uses as standard equipment binocular stereo microscopes which are able to zoom to higher magnifications. These microscopes are equipped with darkfield illumination, as well as an ultraviolet light filtered overhead light. When grading is performed using a 10x handheld loupe, 'darkfield' illumination is more difficult to achieve. The grader must use a light source in such a way that the base of the stone is lit from the side, and the crown of the stone is shielded from the light.
After thoroughly cleaning the diamond, the diamond is picked up using tweezers in a girdle-to-girdle hold. The grader views the diamond for the first time through the table, studying the culet area of the stone for inclusions. The diamond is then set down, and picked up with the tweezers in a table-to-culet hold. In this position the diamond can be studied from the pavilion side, and the crown side, examining the diamond through each facet for inclusions. Once a sector of the diamond has been thoroughly examined the grader rotates the diamond in the tweezer, so that the neighboring sector can be examined. The grader uses darkfield lighting to reveal characteristics, and alternates to reflected, overhead lighting to ascertain whether a characteristic lies within the stone, on the stones surface, or both. If the grader is using a stereo microscope, they may zoom in to a higher magnification to make closer observations of an inclusion, but then return to 10x magnification to make an assessment of its impact on the clarity grade.[4]
If a stereo binocular microscope has been used, a final assessment using a 10x loupe is performed before the final judgment is made on the clarity of the stone. The grader first decides the clarity category of the diamond: none (FL, or IF for a blemish), minute (VVS), minor (VS), noticeable (SI), or obvious (I). The decision is then made on the grade of the diamond.[4][5]
IA clarity grading is performed under 10x magnification with darkfield illumination. The GIA Laboratory uses as standard equipment binocular stereo microscopes which are able to zoom to higher magnifications. These microscopes are equipped with darkfield illumination, as well as an ultraviolet light filtered overhead light. When grading is performed using a 10x handheld loupe, 'darkfield' illumination is more difficult to achieve. The grader must use a light source in such a way that the base of the stone is lit from the side, and the crown of the stone is shielded from the light.
After thoroughly cleaning the diamond, the diamond is picked up using tweezers in a girdle-to-girdle hold. The grader views the diamond for the first time through the table, studying the culet area of the stone for inclusions. The diamond is then set down, and picked up with the tweezers in a table-to-culet hold. In this position the diamond can be studied from the pavilion side, and the crown side, examining the diamond through each facet for inclusions. Once a sector of the diamond has been thoroughly examined the grader rotates the diamond in the tweezer, so that the neighboring sector can be examined. The grader uses darkfield lighting to reveal characteristics, and alternates to reflected, overhead lighting to ascertain whether a characteristic lies within the stone, on the stones surface, or both. If the grader is using a stereo microscope, they may zoom in to a higher magnification to make closer observations of an inclusion, but then return to 10x magnification to make an assessment of its impact on the clarity grade.[4]
If a stereo binocular microscope has been used, a final assessment using a 10x loupe is performed before the final judgment is made on the clarity of the stone. The grader first decides the clarity category of the diamond: none (FL, or IF for a blemish), minute (VVS), minor (VS), noticeable (SI), or obvious (I). The decision is then made on the grade of the diamond.[4][5]
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
Diamonds Prices Details
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