Sending stones back to the lab for regrading

[kenny]

How often do stones get sent back to a lab because the owner thinks it should get a better grade?

10% of the time?
1% ?
0.1%?

Of all those sent back how often is the grade changed?

 

[gemologic]

don''t know that exact answer kenny but here is what happens when you send it to a different lab:....

Is Diamond Grading Absolute?
and the 4 C''s

Respected laboratories can differ and it is acceptable in the trade. Here we find an important stone with two certificates...



PROPERTY FROM THE MARION RUMSEY CARTIER COLLECTION AT SAINT LOUIS UNIVERSITY
AN EXQUISITE SINGLE-STONE DIAMOND RING
Set with a cushion-cut diamond, weighing approximately 19.01 carats, flanked by baguette-cut diamonds, mounted in platinum.

With certificate 11202340 dated 25 July 2000 from the Gemological Institute of America stating that the diamond is G color, VS2 clarity; accompanied by a working diagram indicating that the clarity may be improvable.

With certificate 0102142 dated 19 February 2001 from the Gübelin Laboratory stating that the diamond is F color, SI1 clarity; accompanied by a letter stating that the 19.01 carat diamond described in Gübelin Gem Lab Diamond Report No. 0102142, based on its infrared spectrum, is classified as type IIa.

Magnificent Jewels, Christie''s New York, Rockefeller Plaza, April 11, 2001 Estimate $US 500,000 - 600,000, Price Realized $US545,000

 

[Paul-Antwerp]

Date: 11/13/2006 2:08:25 PM
Author:kenny
How often do stones get sent back to a lab because the owner thinks it should get a better grade?

10% of the time?
1% ?
0.1%?

Of all those sent back how often is the grade changed?

My guestimate would be around 0.001% or less.

Most labs inform you of the grade, and you have the option to have specific points re-checked. After this, most offices generally accept the grade, and work with it. Unless they see an option to improve the grade with a small re-cut (improving clarity or cut).

However, some years ago, I am sure that New York wholesalers would buy stones with HRD-reports in Antwerp, to just throw away the report, and have the stone graded by GIA, very often getting a better colour-grade for the stone, especially in the H-I-range. If they bought well, and got an H-colour out of 50% of the stones, that they bought with I-colour-report, it was worth the trouble. I am not sure whether this is still possible now.

Live long,

 

[mrssalvo]

I don''t know the answer but my stone was originally graded by AGS as an H SI1. It was sent back for a new cert this past july and came back a G SI1. I''m certainly not complaining