Comparison of Diamonds using ImaGem’s Direct Measurement of Light Behavior
| Poor | Fair | Good | Very Good | Excellent | |
| Brilliance |  <100 |
 100 – 110 |
 110 – 120 |
 120 – 150 |
 150 – 205 |
| Sparkle |  <10 |
 10 – 20 |
 20 – 40 |
 40 – 70 |
 70 – 120 |
| Intensity |  <110 |
 110 – 115 |
 115 – 125 |
 125 – 160 |
 160 – 430 |
Overall Light Behavior categories are as follows:
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Excellent + grade is assigned to a diamond with Excellent Brilliance, Sparkle and Intensity Grades.
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Excellent grade is assigned to a diamond with 2 Excellent Grades and 1 Very Good Grade on Brilliance, Sparkle and Intensity.
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Very Good + grade is assigned to a diamond with Very Good or better Brilliance, Sparkle and Intensity Grades.
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Very Good grade is assigned to a diamond with at least 2 Very Good or better grades and 1 Good grade.
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Good grade is assigned to a diamond with at least 2 Good or better Grades and 1 Fair grade.
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Fair grade is assigned to a diamond with at least 2 Fair or better grades and 1 Poor grade.
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Anything below these grades falls under Poor Overall Light Behavior Grade.