Colored Gemstone Grading in a Nutshell

Overall Grade

• Excellent: Outstanding and flawless in all dimensions. This quality is rarely seen in jewelry and is mostly acquired by collectors or long term investors.
• Very Good: Above average in all dimensions with one or two minor flaws.
• Good: Average quality with strengths and weaknesses.
• Fair: Average quality with one or two obvious flaws.
• Poor: Major imperfections.

Clarity

• Free of Inclusions: No inclusions are visible under a 10fold lens
• Very Lightly Included: The trained eye perceives inclusions only with the lens and in some light conditions
• Lightly Included: Only a 10fold lens reveals minor inclusions (not visible to the naked eye, often called "eye clean")
• Moderately Included: Inclusions are visible to the unaided eye but do not harm the stones beauty (often called "nearly eye clean")
• Heavily Included: Inclusions are obvious and influence the stones appearance (often called "included")

Color Grade

• Excellent: Exactly the color everybody wants.
• Very Good: Attractive and well saturated color. Suitable secondary hue.
• Good: Fine main color but strong secondary hue. Off-color but charming
• Fair: Off-Color in this variety, excessive or unsuitable secondary hue and/or much gray
• Poor: Strongly washed out off-color

Tone

• 0-35 (Very Light to Light): Brightest hues. Bordering to colorless in the extreme (0). The appearance is dominated by luster and clarity, not color. Inclusions are very visible. Mostly desired in yellow, and partly pink.
• 35-60 (Light-Medium to Medium): Colors are not yet fully saturated but never too dark. Mostly desired in yellow, pink, green and partly blue
• 60-85 (Medium-Dark): Most varieties are wanted in these tones. Colors are fully developed but not overly dark. For luster to be lively the gem needs a good crystal and cut. Inclusions become less and less visible. Very desired in red, blue, purple and partly green
• 85-100 (Dark): Gemstones in deepest hue, bordering to black in the extreme (100)

Cut

• Excellent: Innovative cut, mostly precision cutting, especially beautiful and flawless in any dimension. A work of art.
• Very Good: Flawless in all dimension.
• Good: Flawless in all but one dimension (say, depth or symmetry)
• Fair: Flawed in two dimensions (say, depth and symmetry)
• Poor: Flawed in several dimension typically chipped and scratched surfaces

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