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Crown and Pavilion Combinations

bearcub907

Rough_Rock
Joined
Feb 21, 2016
Messages
24
Hi Everyone,

I tried searching previous threads about this topic, but couldn't find the answer to my question.

What combination of Crown and Pavilion angles are ideal?

From what I've gathered so far:

C - 34.5 / P - 40.8 (most ideal)
C - 34.5 / P - 41
C - 34 / P 41

Thanks everyone.
 

kenny

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
28,175
bearcub907|1457393615|4001247 said:
Hi Everyone,

I tried searching previous threads about this topic, but couldn't find the answer to my question.

What combination of Crown and Pavilion angles are ideal?

From what I've gathered so far:

C - 34.5 / P - 40.8 (most ideal)
C - 34.5 / P - 41
C - 34 / P 41

Thanks everyone.
If, as I suspect, you are talking about round diamonds use the HCA.
Why? Because the most important four specs, Depth%, Table %, Crown Angle, and Pavilion angle all interact.

https://www.pricescope.com/tools/hca

It's too complicated to work out in your brain.
The HCA is a math thing that works it out and delivers a score.
Reject rounds that score over 2.0.
On rounds that score under 2.0 move on to step 2 ... the Idealscope pic.

https://www.pricescope.com/tools/ideal-scope

This is essential because the HCA is a rejection tool, not a final selection too.
Compare the Idealscope pic to this chart:

http://ideal-scope.com/reference-chart-ideal-scope-images/

idealscope_10.png
 

bearcub907

Rough_Rock
Joined
Feb 21, 2016
Messages
24
Sorry but now I'm getting a little confused.

I followed what the above post recommended - plug in dimensions into HCA. Initially I was only looking for diamonds within the ideal range, C - 34-34.9 and P 40.6-41. But then I just started randomly plugging in diamonds that I came across within my budget.

And the tool showed diamonds that were < 2.0 with crown angles of 33.5 and pavilion of 41.0 or crown 35.5 and pavilion 40.6
I thought we wanted to keep within the ideal ranges Crown 34-34.9 and pavilion 40.6-41

Thoughts??
 

kenny

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
28,175
bearcub907|1457398503|4001276 said:
Sorry but now I'm getting a little confused.

I followed what the above post recommended - plug in dimensions into HCA. Initially I was only looking for diamonds within the ideal range, C - 34-34.9 and P 40.6-41. But then I just started randomly plugging in diamonds that I came across within my budget.

And the tool showed diamonds that were < 2.0 with crown angles of 33.5 and pavilion of 41.0 or crown 35.5 and pavilion 40.6
I thought we wanted to keep within the ideal ranges Crown 34-34.9 and pavilion 40.6-41

Thoughts??
Again HCA is only step 1 of a 2-step process and a reject tool not a final acceptance too.
Those you found may have bad Idealscope images.

Plugging certain ranges for only two of the HCA's four numbers is not useful.
All four numbers interact in a complex way.
Only the fancy math of the HCA, (or your math-genius brain) can take all four numbers into account.

By posting the ranges it gives the impression that ALL diamonds for which the four numbers fall within those ranges are good to go is misleading.


I don't even bother remember or posting the ranges for the four numbers that others post.
The HCA does it all for you and finds the best combinations, and besides the final score also rates four other qualities, light Return, Fire, Scintillation, and Spread.

Example:

screen_shot_2016-03-07_at_5.png
 

flyingpig

Ideal_Rock
Premium
Joined
Nov 7, 2015
Messages
2,175
bearcub907|1457398503|4001276 said:
Sorry but now I'm getting a little confused.

I followed what the above post recommended - plug in dimensions into HCA. Initially I was only looking for diamonds within the ideal range, C - 34-34.9 and P 40.6-41. But then I just started randomly plugging in diamonds that I came across within my budget.

Google "complete explanation of ags cut system". You will see so much information on light performance and cut grade

And the tool showed diamonds that were < 2.0 with crown angles of 33.5 and pavilion of 41.0 or crown 35.5 and pavilion 40.6
I thought we wanted to keep within the ideal ranges Crown 34-34.9 and pavilion 40.6-41

Thoughts??
33.5/41 and 35.5/40.6 can be spectacular. 40.8/34.5 is just a safer bet in many cases, but not always true, depending on table percentage and other factors (star length/lower girdle height). Some people actually expand the ideal range to include 33.5 and 35.5 crown. Even, 33 and 36 crown can be beatiful, as long as table and pav angle complement.

No single screening tool is perfect. HCA has its own set of limitations. So do the so called "ideal" ranges.
It is good to use ALL tools available. AGS/GIA proportion chart, HCA score, IS/ASET image, visual inspection, etc
.
 

Diamond_Hawk

Brilliant_Rock
Trade
Joined
Apr 8, 2014
Messages
1,221
bearcub907|1457398503|4001276 said:
Sorry but now I'm getting a little confused.

I followed what the above post recommended - plug in dimensions into HCA. Initially I was only looking for diamonds within the ideal range, C - 34-34.9 and P 40.6-41. But then I just started randomly plugging in diamonds that I came across within my budget.

And the tool showed diamonds that were < 2.0 with crown angles of 33.5 and pavilion of 41.0 or crown 35.5 and pavilion 40.6
I thought we wanted to keep within the ideal ranges Crown 34-34.9 and pavilion 40.6-41

Thoughts??
I think the difficulty is that you are only citing 2 of the important measurements. CA and PA are, of course, very important. But the table % and depth % are vital as well. It is a matter of how the Proportions of the total diamond work together, no so much just how the Crown and Pavilion Angles interact.

Think of it this way:

Is a man who is 6' 2" and weighs 235 pounds in shape or obese? Well, according to the Body Mass Index Calculator - this man is obese. Do we have enough information to definitively state that case? I don't think so.

You have to consider ALL the factors, not just two. If we investigate and find out that he is an NFL linebacker with a body fat percentage around 10% who can run a 40 yard sprint in under 5 seconds and bench press his own weight 35 times we are going to conclude that he is not, in face, obese.

Still- a quality image of him will help confirm our conclusions.

Utilize all of the numbers you can, and then add reflector images (Ideal-Scope and ASET) into the mix if possible to find the greatest possible light performance.
 
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