Sarin Discrepancies?

[cmcwill]

Hi everyone,
I was just wondering why some Sarin Reports are way off what the GIA report lists as table, and sometimes off for depth? Is Sarin not very accurate at determing the table %? Which would you trust more?

Thanks!
Colleen

 

[pqcollectibles]

Specs are rounded on GIA Certs. For example, a 56.8% table would be reported as 57% on the GIA Cert.

 

[niceice]

There is usually some sort of minor discrepency between the various proportions analysis, but major discrepancies are usually the result of a poorly calibrated machine or a dirty stone... For instance, if the GIA diamond grading report indicates that the total depth of the stone is 60.3% and the Sarin / OGI results say that it's 60.4% we wouldn't sweat it, but if the results indicate something like 60.8% then you can bet that something is off... And such differences can result in major changes to the other measurements because the results are mathematical averages... For instance, earlier this week we received a diamond from a supplier which had a total depth of 61.4% and a table diameter of 55% according to the GIA diamond grading report, the cutter told us on the telephone that the diamond had a 34.8 degree crown angle and a pavilion angle of 40.8 degrees which is right on target from our perspective... We put the diamond on our machine which is calibrated weekly using specific "master stones" and we get measurements which match those on the GIA lab report, but we get a pavilion angle of 41.5 degrees which is completely uncceptable to us and for a moment we're kind of stunned, but then we realize that the cutter's Sarin results indicate that the total depth of the stone was 60.8 degrees which is "off" and therefore so were the other measurements... Thus the "zero" cut wasn't - not even close, and it made us wonder how many people have purchased diamonds from "virtual dealers" who drop shipped diamonds to clients based upon inaccurate Sarin / OGI measurements which really aren't zero cuts at all? Check those measurements people! Make sure that ALL of the measurements indicated on the Sarin / OGI results are within very close tolerance to those listed on the lab report...

 

[Rhino]

I'd ditto that. I have even seen some MegaScopes done by appraisers that were waaaay off. You can generally tell how good the calibration is by how close the estimated weight by volume (as measured by the OGI/Sarin) is to the actual weight of the diamond being scanned too.




It is not uncommon however for a Sarin or OGI table measurement to be off by 1% due to the rounding off that is done by the labs and generally .1 or so difference in the angle measurements.




Interesting story R/T about that diamond.

 

[cmcwill]

Thanks guys!
I was just noticing some not matching up, but didn't know to what degree there was 'wiggle' room. Thanks for answering my question!
Colleen