On most grading reports both blemishes and inclusions are plotted for the face-up and pavilion views of the stone. In general, blemishes are plotted in green, inclusions are plotted in red and extra facets and some naturals are plotted in black. Often, to avoid a messy looking plot, pinpoints, clouds and other minor details of clarity are not plotted, but indicated under "Comments:" at the bottom of the report.
Blemishes
Abrasions: tiny nicks on facet junctions or the culet; caused by wear or coming in contact with other diamonds.
Extra Facets: small facets placed to remove imperfections; not part of the cutting style. (Not to be confused with Added Facets which are added symmetrically and are part of the cutting style.)
Naturals: part of the original crystal surface remaining on the polished stone, frequently in the area of the girdle.
Polish Lines and Marks: tiny parallel lines or surface clouding left by irregular polishing or excessive heating during polishing, respectively.
Rough Girdle: a grainy or pitted girdle surface usually caused by poor workmanship.
Surface Graining: structural irregularities in crystal growth; may appear as faint lines, causing grooved or wavy surfaces and often cross facet junctions.
Inclusions
Bearding: tiny feathers extending inward from a bruted girdle surface. (Bruting is the process of rubbing two diamonds together to achieve the rounded shape of the diamond.)
Cavities and Chips: large/deep openings, and small/shallow openings in the diamond's surface, respectively.
Clouds: hazy or milky areas of many very small, usually crystalline inclusions.
Feathers: cleavages or fractures often white and feathery in appearance. (There are 4 cleavage planes in diamond, which run in octahedral directions. Fractures are breaks along planes other than cleavage planes and may alternate with them to form step-like feathers.)
Included Crystals: mineral crystals, such as garnet or peridot, contained inside a diamond.
Indented Naturals: natural rough surfaces that penetrate the stone and may distort the girdle outline.
Internal Graining: regions of irregular crystal growth that may appear as milky or colored lines or streaks, or may be reflective.
Laser Drill Holes: a tiny tube made by a laser; the surface opening may resemble a pit, while the tube usually resembles a needle.
Needles: needle-shaped included crystals.
Pinpoints: areas of minute, dot-like inclusions.
Twinning Wisps: cloudy areas produced by distorted crystal growth.
Grading Clarity
All clarity grading is performed at 10-times magnification using a hand loupe or gemological microscope under both artificial daylight and darkfield illumination conditions. Reflected light is used to detect and evaluate blemishes and darkfield light for inclusions. It's the face-up view that usually sets the clarity grade, however the face-up, pavilion and table-to-culet views are all taken into consideration during grading.
Clarity grades are largely determined by the collective visual appearance that a stone's inclusions exhibit in relationship to the size and shape of the stone. It is the consideration of the size, position, number, color/contrast and nature of these inclusions, which leads to the final clarity grade. Frequently, it is possible to quickly key on the most obvious inclusions seen in the face-up position in making a final grade determination. However, the higher clarity grades (Fl, IF, VVS1/2) are more difficult to distinguish than the lower (VS1/2, SI1/2, I1/2/3) because more care must be given to avoid overlooking small characteristics.
