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Grading Lab Survey
Introduction
Method of Survey
Results
- Clarity and Color
- Cut Grades
- Clarity Plots
- Laser Inscription
- Girdle Thickness
- Measurements
- Pricing
 - Price Differences
Discussion
- Brand Value
- Appraisal
Conclusion
Acknowledgements
Appendix I
Appendix II
Appendix III
Appendix IV
Appendix V
Diamond Tutorial
 
    
3.6. Measurements and Depth Percentage
 
All measurements and proportions are shown in Appendix III.
 
Confirming the largest and smallest diameter of a diamond with a micrometer is difficult. This survey did not attempt to check the accuracy of diameter measurements, which are generally reported by a Sarin Technologies scanning device. Diameter variations of 0.01 to 0.03mm were common. Depth measurements varied from none to 0.03mm, with an average of less than 0.02mm. It is a common practice to identify a diamond, or to ensure that a diamond matches its report, by comparing its measurements to those on the certificate.
 
Measurement variations led to inconsistencies in depth percentages, which varied by an average of 0.4% and as much as 0.7% between different laboratories. Depth percentages and table size ratios are used by many buyers to make purchasing decisions; therefore measurement accuracy affects a diamonds market value.
 
 
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