joeq
Rough_Rock
- Joined
- Sep 30, 2003
- Messages
- 42
I have been looking closely at the proportions of some diamonds and I''ve noticed that they don''t always add up.
For example, it is physically impossible to have the combination of crown pavilion angles, table size, total height, and pointed culet that the certificate states. The difference is small, but definitely there. I would think that this is due to imprecisions in the measurement of the diamond.
So, which measurements are typically more accurate than others? I would guess that carat weight, diameter, and total height would be the easiest to measure and therefore the most accurate. I''m guessing that the specific angles are the most difficult. Nowadays, jewelers just drop it in a Sarin or OGI to get the numbers, so I guess I''m asking what level of accuracy to expect from those machines.
It occurred to me that the difference could also be due to using different orientations for each measurement in a non-symmetrical diamond. Are the measurements averages across the diamond?
I would guess that on a Sarin machine, all of the numbers on the report are from actual measurements. On an AGS cert, are ALL the numbers there from actual measurements or are any of them extrapolated? Does AGS use Sarins to get their numbers? Or does it depend on the specific AGS lab?
I also wonder about the precision of the measuring process. If you run two Sarins on a stone, how much variation will you see? How about running the same stone on two different machines? With something like crown angle, when I see an angle of 34.63, how many of those digits are significant?
(Of course, .01 crown angle isn''t going to make a bit of difference. I''m just curious as I try to model these diamonds, because you need to extrapolate the measurements that you don''t have.)
I''m guessing Garry has lots of experience in this area
. Garry, what do you think?
For example, it is physically impossible to have the combination of crown pavilion angles, table size, total height, and pointed culet that the certificate states. The difference is small, but definitely there. I would think that this is due to imprecisions in the measurement of the diamond.
So, which measurements are typically more accurate than others? I would guess that carat weight, diameter, and total height would be the easiest to measure and therefore the most accurate. I''m guessing that the specific angles are the most difficult. Nowadays, jewelers just drop it in a Sarin or OGI to get the numbers, so I guess I''m asking what level of accuracy to expect from those machines.
It occurred to me that the difference could also be due to using different orientations for each measurement in a non-symmetrical diamond. Are the measurements averages across the diamond?
I would guess that on a Sarin machine, all of the numbers on the report are from actual measurements. On an AGS cert, are ALL the numbers there from actual measurements or are any of them extrapolated? Does AGS use Sarins to get their numbers? Or does it depend on the specific AGS lab?
I also wonder about the precision of the measuring process. If you run two Sarins on a stone, how much variation will you see? How about running the same stone on two different machines? With something like crown angle, when I see an angle of 34.63, how many of those digits are significant?
(Of course, .01 crown angle isn''t going to make a bit of difference. I''m just curious as I try to model these diamonds, because you need to extrapolate the measurements that you don''t have.)
I''m guessing Garry has lots of experience in this area
