40.6 vs 41.0 pavilion angle

[Serg]

At 5m the diamond even a 5ct is a tiny dot, the contrast between that dot and what is behind determines if it stands out or not. Since the eye will not pick up fine details the brightness is a blurred average of the dot relative to the background.
Obstruction will play little part in it.
However shallow pavilions are more directional, there could be an advantage there.
LGD is not that expensive, Garry consider having some cut and play with them?
You could even send them to others to look at.
That was not practical with mined but 4-6 1ct LGD might make it affordable?

We (OctoNus, Lexus, Garry) did it 15 years ago.

OctoNus : Master Stone Set

See MSS samples 4 and 9.




It is a very long story. Now it can be done more precisely and for larger stones if we use LGD (Lab-Grown Diamonds). LGD is much more convenient for such tests, not only because it's cheaper but also because there are fewer issues with transporting them across different countries' borders.

The problem is not in cutting more samples (we cut them constantly; in the last 2 months, we've cut nearly 10 3ct LGD diamonds to study the impact of Stria on the Optical Performance of LGD diamonds). The challenge lies in organizing scientifically valid tests based on consumer viewing of real diamonds. This is an extremely complex and expensive procedure. This process is much costlier than working with samples, even if they are natural diamonds.

Personally, I have long abandoned the practice of surveying consumers based on viewing real diamonds. It's much simpler to show and discuss Dibox2.0 movies.

 

[Garry H (Cut Nut)]

I would LOVE to participate in this pay (shipping?) to play this lab grown different cut diamond game, if it ever fruits.

Especially if it included Garry’s shallower is better for earrings cut (extreme and moderate version), a good but typical gia xxx, a nice 60/60, and a super ideal.

This has become a thread jack re the shallow pavilion stones. The diamonds I propose for earrings have 41 to 41.3 degree pavilion angles.
The stone I used for Drena earrings test was a traded in stone. Not a stone I would recommend but an extreme example for the purpose.

 

[josieKat]

I would LOVE to participate in this pay (shipping?) to play this lab grown different cut diamond game, if it ever fruits.

Especially if it included Garry’s shallower is better for earrings cut (extreme and moderate version), a good but typical gia xxx, a nice 60/60, and a super ideal.

I've actually wondered whether those in the diamond industry have ever or would collaborate with cognitive/perceptual psychologists to study both perceptions and preferences. I'm sure there's lots of marketing research out there, but, e.g., what is the true jnd (just noticeable difference) for three-dimensional diamond size, or for degree of brilliance? I have to admit I haven't done a search of the literature recently but I recall not finding anything quickly when I did search years ago (I'm a cognitive scientist and teach sensation and perception, so this question came to mind early on).

 

[Serg]

I've actually wondered whether those in the diamond industry have ever or would collaborate with cognitive/perceptual psychologists to study both perceptions and preferences. I'm sure there's lots of marketing research out there, but, e.g., what is the true jnd (just noticeable difference) for three-dimensional diamond size, or for degree of brilliance? I have to admit I haven't done a search of the literature recently but I recall not finding anything quickly when I did search years ago (I'm a cognitive scientist and teach sensation and perception, so this question came to mind early on).

Did you check
How diamond performance attributes: Brilliance,Scintillation and Fire depend on human vision features
?

 

[Serg]

This has become a thread jack re the shallow pavilion stones. The diamonds I propose for earrings have 41 to 41.3 degree pavilion angles.
The stone I used for Drena earrings test was a traded in stone. Not a stone I would recommend but an extreme example for the purpose.

It's easy to be misled by focusing solely on the pavilion angle.
For example P41.2 Cr32.5 looks very similar to P40.8 Cr34.5,
while P41.2 Cr30.5 resembles P40.4 Cr34.5, essentially making it a Shallow RBC despite having a pavilion angle of 41.2.
The pavilion angle alone does not determine whether a diamond looks like a Shallow or a Deep one.The combination of crown and pavilion angles is crucial.For the sake of discussion and comparison, it's helpful to convert the stone's parameters to an equivalent diamond with a crown angle of 34.5, using a 1:5 ratio.In other words, for every 0.1-degree decrease in the crown angle, you should increase the pavilion angle by 0.5 degrees (possibly a more accurate ratio is 2:9).

This is precisely why it's important to consider how a diamond's beauty changes when you alter the pavilion angle while keeping the crown angle fixed at 34.5 degrees.It's crucial to examine and discuss the pros and cons of combinations like P41Cr34.5 and P40.6Cr34.5 compared to P40.8Cr34.5.If someone doesn't see the difference with such small changes in the pavilion angle, you can begin by comparing P41.2Cr34.5 to P40.4Cr34.5, both with each other and with P40.8Cr34.5.

If one were to evaluate and sort five combinations based on optical performance - P40.4Cr34.5, P40.6Cr34.5, P40.8Cr34.5, P41Cr34.5, P41.2Cr34.5 - this would allow for the use of the 1:5 (2:9) ratio to obtain equivalent proportion ratios and ultimately appreciate a broader range of crown and pavilion angle combinations around P40.8 Cr34.5.

 

[josieKat]

Did you check
How diamond performance attributes: Brilliance,Scintillation and Fire depend on human vision features
?

I did not - I was checking in Psych journals! Thank you for the reference! (I keep contemplating pulling in diamond perception as an example in my course.)