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Gem grading
Unlike diamonds there is no one standard for color stone grading. Therefore color stone grading is subjective. One person's opinion may vary slightly compared to another person's opinion.
As part of the description, most of the gemstones listed have a description of its color and clarity. Color is described in terms of tone (brightness), saturation and one of 31 hue descriptions as used by the GIA.
Tones (lightness to darkness), shown here in blue are as follows:
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Colorless |
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Extremely Light |
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Very Light |
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Light |
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Medium Light |
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Medium |
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Medium Dark |
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Dark |
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Very Dark |
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Extremely Dark |
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Black |
Saturation (shown here in blue) is an indication of how "strong" or "vivid" a color is. Saturation is listed as
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Gray (dull) |
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Grayish |
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Slightly Grayish |
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Very Slightly Grayish |
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Moderately Strong |
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Strong |
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Vivid |
Hues are described as the color itself:
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Red |
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Orangy Red |
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Red-Orange or Orange-Red |
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Reddish Orange |
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Orange |
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Yellowish Orange |
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Orangy Yellow |
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Yellow |
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Greenish Yellow |
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Yellow-Green or Green-Yellow |
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Strongly Yellowish Green |
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Yellowish Green |
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Slightly Yellowish Green |
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Green |
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Very Slightly Bluish Green |
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Slightly Bluish Green |
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Strongly Bluish Green |
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Green-Blue or Blue-Green |
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Very Strongly Greenish Blue |
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Greenish Blue |
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Very Slightly Greenish Blue |
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Blue |
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Violetish Blue |
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Bluish Violet |
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Violet |
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Bluish Purple |
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Purple |
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Reddish Purple |
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Purple-Red or Red-Purple |
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Strongly Purplish Red |
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Slightly Purplish Red |
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Red |
Clarity is a subjective term, however the following is how we describe clarity:
Opaque, meaning the stone will not transmit light through it.
Translucent, or cloudy, meaning that the stone transmits light on the edges, but you cannot see clearly through it.
Heavily Included, meaning that the stone is transparent, but the stone is littered with inclusions, which are very visible without magnification.
Moderately Included, meaning that the stone is transparent, but there are several inclusions, which are visible without magnification.
Slightly Included, meaning that the stone has some very minor inclusions which may be visible without magnification.
Very Slightly Included, or eye-clean, meaning that the stone has some very minor inclusions that are not readily visible without magnification. Some inclusions may be visible without magnification once you see them under magnification and know exactly where to look.
Very Very Slightly Included, meaning that the stone has some very very minor inclusions which are difficult to see under 10 power magnification.
Flawless, meaning that there are no inclusions visible under 10 power magnification.
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