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Measuremnt Disagrees With Report


Bagua
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Hello,

 

I recently purchased a diamond of pretty good quality, I thought. My only concern was that one measurement did not match exactly with the GIA report. When the sales lady used a dial gauge to measure the total depth, it read ~4.22mm instead of the 4.27mm reported, no matter how she re-adjusted and re-positioned. But the weight was correct, and the other measurement on diameter was about right, a bit over 7 vs. the reported 7.03-7.07.

 

My questions are: How precise is the dial gauge? What could be the problem: measurement position tilt(but it was against the flat table area), a chipped culet that caused the shortened depth, or others? How critical was this? Am I being too picky? I'd appreciate your precious inputs here. Thanks.

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A chipped culet or any other damage to the stone since GIA looked at it is easy to spot with magnification and your appraiser should have no problem pointing it out to you when they inspect it. Similarly, if there is any serious question whether it's the correct the stone the appraiser should be able to check it against other attributes

 

Dial gauges get out of calibration easily and using them properly is not nearly as straightforward as people tend to think. 0.05mm isn't a lot for that error and I would believe the numbers on the GIA far more than from a dial gauge.

 

Neil

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Two points to consider:

 

1. Guages have built in variance.

 

2. GIA rounds off to the next highest number.

 

Taken together there will always be a slight but insignificant discrepancey between GIA's numbers on their Lab report to the numbers recorded by Sarin, Megascope, or manual guage.

 

Nothing to be concerned about.

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