No phantom of cheating on cut any more? We seek your input.Part2

[OoohShiny]

Thank you for the detailed explanation, Serg!

This discussion is very useful for increasing understanding of crown/pavilion angle effects - although it is also challenging, because the 'PS recommendations' usually limit Pavilion angle to 40.6-40.9!

IIRC your other posts are also challenging regarding 'fish-eye'-effect stones (from steep/deep stones?) potentially looking better / having more 'life'/sparkle/fire at tilt angles - it makes me ask the question "Does a 'fish eye' or 'ring of death' stone actually perform better over a wider range of angles?" !

 

[Serg]

Thank you for the detailed explanation, Serg!

This discussion is very useful for increasing understanding of crown/pavilion angle effects - although it is also challenging, because the 'PS recommendations' usually limit Pavilion angle to 40.6-40.9!

" !

@OoohShiny

Do you know real source or reason of such pavilion limitation?
Did anybody see any real proof of such limitation without link to monoscopic structure lights as IS, ASET, H&A?
Did you see any blind comparison test between P40.6Cr34.5 and P41.2Cr34.5?

 

[OoohShiny]

@OoohShiny

Do you know real source or reason of such pavilion limitation?
Did anybody see any real proof of such limitation without link to monoscopic structure lights as IS, ASET, H&A?
Did you see any blind comparison test between P40.6Cr34.5 and P41.2Cr34.5?

My understanding (gained from Pricescope!) is that shallow pavilions (<=40.6) are at risk of leakage and should therefore be avoided - because the critical pavilion angle is 40.45degrees, and due to scanner error and Grading Report averaging / rounding of the eight pavilion facet angles, it is possible that one or more of the facets is under 40.45degrees.

There may also be potential issues with obstruction in shallow crown/shallow pavilion diamonds (with short LGFs and/or small tables??) because of too much obstruction under the table making the centre look too dark, IIRC?


At the other extreme, my understanding is that deeper pavilions (>=40.9, and/or when considered with a fixed crown height) can cause light to leak out of the sides of the stone and/or cause 'fish eye' effects / windowing showing one's finger, for example. (I think?! )


But... as you say, assessment of stones is currently carried out using monocular tools (IS, ASET, H&A, photograph, video, HCA(?)) which does not adequately assess / display the effects visible using binocular vision (scintillation, areas of high contrast between brightness/obstruction, 'beauty', etc.)

What I get from your questions and your images is that perhaps a deeper pavilion (which performs 'poorly' in terms of monocular ASET/IS/HCA, with a 'ring of darkness/leakage' under the table and a higher HCA score) might actually perform very nicely when viewed in 'real life' with binocular vision - in terms of both 'beauty' and empirical assessment of light performance, and when viewed at tilt angles (not just head-on).

Is that a correct assessment??

 

[OoohShiny]

By sheer coincidence, an excellent example of the differences between two stones that are close to what we are discussing!

https://www.pricescope.com/community/threads/earrings-again-wf-aca-vs-ags000.251712/#post-4620266

The AGS 000 is on the left, it was in my wife’s pendant, I am purchasing the ACA on the right with the thought of making matching earrings. My OCD is getting the best of me. Wondering if I should attempt to sell the AGS 000 stone and go with two ACA stones. Just wondering if I am going out of my way to make my life difficult, lol.

The AGS 000 is from 1998, CA 34/PA 41.2, that was the original specs, now days, 41.2 is considered out of range.

I see the ACA has a 56 table, 61.6 depth, 34.6 crown, 40.7 pavilion & 77 LGF.