Method of Survey

This survey was funded by Pricescope, including the expenses of two additional grading reports and shipping of the diamonds. None of the surveyed labs were made aware of the survey.

Three labs were surveyed:

  1. GIA-GTL.
  2. AGSL.

  3. EGL USA.

These three labs were chosen because there are reasonable sized commercial data bases of pricing information to enable cost comparisons.

Pricescope approached three independent diamond vendors:, and to provide diamonds from their inventories. These stones had already been graded by either GIA-GTL or AGSL and they were then sent to the two other grading laboratories. The vendors were aware of the purpose of this experiment and the need for secrecy. They knew that other vendors would be participating in this survey, but they were not informed of the identity of the other vendors.

In total 17 round brilliant cut diamonds were selected for the survey, but one was inadvertently sent to GIA-GTL twice (and received different clarity grades). They ranged from 0.6 -1.25 carat, E – J color and VVS2 – SI2 clarity ranges. The sizes and qualities were chosen to represent frequently traded range of diamonds. The vendors were asked not to deliberately select stones that they considered to be border line examples or stones that in their opinion had been “missgraded”. See Appendixes I – V for all diamonds’ details.

Each of the diamond vendors independently submitted their already lab graded diamonds to two additional grading labs. Namely:

    selected 6 diamonds (5 with AGSL and 1 with GIA-GTL reports) and submitted them to GIA and EGL USA

    selected 4 diamonds with GIA-GTL reports and submitted them to AGSL and EGL USA

    selected 7 diamonds with GIA-GTL reports and submitted them to AGSL and EGL USA.

All diamonds and all 3 grading reports were then shipped to David Atlas, GG, NGJA, ASG Accredited Gem Appraisers, Philadelphia, PA for additional professional evaluation and to review the grading results.



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