AGS vs. Sarin numbers

[kindred]

I am looking at a diamond that shows different numbers on the AGS report than the Sarin report. This affects the HCA score, as well. Which numbers should I believe?

AGS says:
Depth: 61.5
Table: 56.9
Crown Angle: 34.9
Pavilion Angle: 40.9

This brings up HCA of 1.9
Light Return: Excellent
Fire: Very Good
Scintillation: Very Good
Spread: Very Good



Sarin says:
Depth: 61.4
Table: 57.4
Crown Angle: 34.8
Pavilion Angle: 40.8

This brings up HCA of 1.5
Light Return: Excellent
Fire: Excellent
Scintillation: Excellent
Spread: Very Good

 

[stone-cold11]

Err.. why? both numbers are below HCA 2 anyway. HCA score is only a rejection tool, remember that.

I would believe AGS, Sarin depends on how well it is calibrated before it measures your stone, might be some time since it was last calibrated, etc...

 

[kindred]

I was thinking it was better to have a Fire and Scintillation score of excellent than very good. Is that not so?

 

[stone-cold11]

You still can't tell from the numbers.

If you really want to believe in a number, AGS is safer. Ask yourself, will a lab calibrate it's instrument more carefully, frequently, because that is it's livelihood and accuracy of that data is of great importance because that is what their Cut Performance is based on or a Jeweler, who usse that to provide more data, probably do not even have on employment, a trained technician to maintain, calibrate that equipment in question, just requesting servicing from the vendor once in a while?

 

[kindred]

Another diamond I am interested in went from a HCA of 1.7 based on the GIA numbers to a HCA of 2.1 based on the very slightly different Sarin numbers for the crown angle. Which numbers would you trust in this case? I''ve read here that GIA rounds their numbers, so would you trust the Sarin in this case?

GIA says:
Depth: 62.8
Table: 54
Crown Angle: 35
Pavilion Angle: 40.8
HCA score 1.7 Excellent

Sarin says:
Depth: 62.8
Table: 54
Crown Angle: 35.2
Pavilion Angle: 40.8
HCA score 2.1 Very Good

 

[stone-cold11]

Probably, as GIA apparently rounded down the crown angle to 35 degree.

 

[Lorelei]

AGS are the numbers of authority in the first case. Second case hardly any variance where it matters.