Crown/pavilion angle combinations

[Lynn B]

Lynn, if you dont mind what are your specs on that ring?

Always happy to brag, er, I mean SHARE!

2.367 AGS-0 J/SI2
60.5 total depth
55 table
34.4/15.4 crown
40.8/43.1 pav

 

[JohnQuixote]

Date: 10/11/2005 9:49:51 PM
Author: Garry H (Cut Nut)

BTW the ideal-scope image that John posted is of a diamond that has some minor facets adjusted to a shallower angle, so it is kinda cheating to show that those proportions do not leak.

Or maybe not Garry. You see, this is the problem with assuming the listed proportions are exact and subject to general rules in any system. The diamond is listed on the AGS document as 40.9/35. We always list diamond numbers on our website as per the AGS or GIA grading report numbers. That is our default on accuracy, particularly since AGS uses helium.

However, our top-end Sarin machine tells us this diamond is a 40.8/34.8. This after running it twice.

Either way, the light performance does not lie. This is why I caution people not to make a big deal about tenths of degrees. Look at the reflector image or, better yet, look at the DIAMOND.

See the difference slight discrepancies like this can make. AGS Proportions and HCA:

 

[JohnQuixote]

And the actual Sarin and HCA:

 

[JohnQuixote]

Date: 10/11/2005 9:49:51 PM
Author: Garry H (Cut Nut)

BTW the ideal-scope image that John posted is of a diamond that has some minor facets adjusted to a shallower angle, so it is kinda cheating to show that those proportions do not leak.

Here is the actual reflector image.

Also Garry - the question about exactness of measurements notwithstanding - you made a statement that some angles were adjusted to be more shallow. In your professional opinion or best guess, can you point out which angle(s) is (are) shallow according to the IS - and at what point do you consider them shallow? Curious about this, as it may be the case and I would like to hear your thoughts.

 

[Garry H (Cut Nut)]

First, I agree with all your above statements John.
In my opinion an ideal-scope on a round diamond is better than a Sarin report every time.
But a 3D model is even better.
I expect that stone has thicker junctions at the minor girdle meets because it has painted upper girdle facets that are maybe 2 degrees shallower than normal.

Haven not got time to model and check - but thats my edjucated guess