Ideal Cut vs Premium Cut for Princess shape

[j123]

Hello Everyone-

This is my first post (of many I''m sure) as I begin my diamond search. I have performed hours upon hours of research to understand the various variables before I start honing in on each variable to narrow down my search. The information on this site is truly amazing.

The one area that seems the most uncertain is cut. I understand that AGA is the only lab to evaluate cut. Here are my questions

1) Why do the table and depth % at https://www.pricescope.com/wiki/diamonds/princess-cut-diamond/ not seem to match the standards for Ideal/premium on JA or other sites? For example, I am looking at ideal cuts at JA with tables of 72% (outside the 62-68%)

2) within a given range (i.e, ideal or premium) is it better to be at the top, middle or end of a range?

3) Is it more important for the table and depth % to be within the range, or is it also the CORRELATION between the two numbers? For example, sometimes the table will be ideal but depth premium. Could that result be worse than both numbers being premium

4) Why don''t I see any website list the crown and pavilion angle?

5) Can the HCA be used for princess? Seems to say only for round.

6) Some pictures seem to have more facets than others, is this possible, and is there a way to know which one technically has the most facets?

I know most of you prefer to focus on the ASET image as opposed to being hung up on numbers, however, I feel I need to better understand this information to help in my analysis and filtering. Especially since most sites dont post ASET and have limits on requests.

Sorry for the long list, just trying to organize the information in my head.

 

[stone-cold11]

1) How each vendor label their stones is their preference. AGS is the only lab that grades princess cut in cut performance and it is not according to just 2 dimensional proportions.

2) No, because there are different ways of cutting a princess.

3) No, not necessary.

4) Because there is no baseline for the angles to be reference to.

5) Yes, HCA is only calibrated for the standard modern 57 facets round cut, even modified cuts, such as solasfera or OEC is not applicable to use on it.

6) Look at the profile, inclusion plot, it should show how many chevron facets is for a given princess. Personal preference on how many chevrons cut you like, also it is related to the size of the stone, a larger stone with 4 chevrons cut can have the same facet size as a smaller stone with a 2 chevron cut.

ASET is the only way to judge a princess on light return because of the different ways each chevron can be angled even with the main facet fixed, this will determine the light performance of the stone.

 

[yssie]

Date: 3/8/2010 5:09:10 PM
Author:j123
Hello Everyone-

This is my first post (of many I''m sure) as I begin my diamond search. I have performed hours upon hours of research to understand the various variables before I start honing in on each variable to narrow down my search. The information on this site is truly amazing.

The one area that seems the most uncertain is cut. I understand that AGA is the only lab to evaluate cut. Here are my questions

1) Why do the table and depth % at http://www.pricescope.com/wiki/diamonds/princess-cut-diamond/ not seem to match the standards for Ideal/premium on JA or other sites? For example, I am looking at ideal cuts at JA with tables of 72% (outside the 62-68%)

2) within a given range (i.e, ideal or premium) is it better to be at the top, middle or end of a range?

3) Is it more important for the table and depth % to be within the range, or is it also the CORRELATION between the two numbers? For example, sometimes the table will be ideal but depth premium. Could that result be worse than both numbers being premium

4) Why don''t I see any website list the crown and pavilion angle?

5) Can the HCA be used for princess? Seems to say only for round.

6) Some pictures seem to have more facets than others, is this possible, and is there a way to know which one technically has the most facets?

I know most of you prefer to focus on the ASET image as opposed to being hung up on numbers, however, I feel I need to better understand this information to help in my analysis and filtering. Especially since most sites dont post ASET and have limits on requests.

Sorry for the long list, just trying to organize the information in my head.

1. Each vendor or reporting authority chooses its own set of standards and ranges for ideal/vg/ex/etc. The particulars of these standards don''t have to match - in fact, they rarely do - it''s why looking at numbers, performance images, and with fancies especially having expert eyes evaluate each stone is invaluable.

2. Again, depends on the range in question.

3. You want crown, pavilion, table, depth to all be in synch with each other - a diamond is a bunch of mirrors and prisms, so the way all the facets interact together is very important - much more so than any one measurement or facet on its own.

4. Some websites will post certs which may contain that info, otherwise a scan will have it

5. HCA for rounds only. You really want an aset for a princess.

6. Different types of princesses - 2, 3, 4 chevron, have different numbers of facets. If you''re looking for big bold flashes of light -well, princess is just a poor choice

, sparkles will be twinklier, more splintery in a diamond of a certain ct wt that has more facets than one with fewer facets.

 

[j123]

Thank you both for the quick reply. So it appears the table and depth numbers will not provide me with useful information in my sorting parameters/evaluation options?

Based on that assumption I, essentially, should filter like this:

1) Set my price limit
2) Set my eye-clean limit
3) Set my color limit
4) Sort possibilities by largest size meeting above criteria
5) Begin evaluation and comparison based on real picture and ASET scan (this assumes symetry and polish will come across based on this visual inspection).

Is this the right way to approach?

I thought I read about criteria where the table should be smalller than depth and table should be less than 75%.....or something like that

 

[yssie]

Sounds like a solid plan!

 

[stone-cold11]

yap, generally table should be smaller than table to get a better chance of having a larger crown height.

 

[j123]

Date: 3/8/2010 6:12:16 PM
Author: Stone-cold11
yap, generally table should be smaller than table to get a better chance of having a larger crown height.

Helpful to know. Any other general rules to consider? Maybe something like table should be within X of depth, or something like that?

 

[yssie]

https://www.pricescope.com/wiki/diamonds/princess-cut-diamond/

 

[Paul-Antwerp]

Date: 3/8/2010 5:59:07 PM
Author: j123
Thank you both for the quick reply. So it appears the table and depth numbers will not provide me with useful information in my sorting parameters/evaluation options?

Based on that assumption I, essentially, should filter like this:

1) Set my price limit
2) Set my eye-clean limit
3) Set my color limit
4) Sort possibilities by largest size meeting above criteria
5) Begin evaluation and comparison based on real picture and ASET scan (this assumes symetry and polish will come across based on this visual inspection).

Is this the right way to approach?

I thought I read about criteria where the table should be smalller than depth and table should be less than 75%.....or something like that

You have already received good replies from SC and Yssie. Just to confirm, you mentioned AGA being the only one to grade cut, it is actually AGS, with AGA having also cut-grading-charts, based upon another approach.

I would however reconsider your strategy. Following these steps, you will likely end up with the cheapest or biggest stone matching your criteria, and passing the ASET as good enough. This might be your goal, no problem.

Another approach would be to contact the vendor, explain him or her what you want and let him give you options to choose from. Chances are that you will get a much better stone.

Live long,

 

[Lorelei]

Date: 3/9/2010 2:47:48 AM
Author: Paul-Antwerp

Date: 3/8/2010 5:59:07 PM
Author: j123
Thank you both for the quick reply. So it appears the table and depth numbers will not provide me with useful information in my sorting parameters/evaluation options?

Based on that assumption I, essentially, should filter like this:

1) Set my price limit
2) Set my eye-clean limit
3) Set my color limit
4) Sort possibilities by largest size meeting above criteria
5) Begin evaluation and comparison based on real picture and ASET scan (this assumes symetry and polish will come across based on this visual inspection).

Is this the right way to approach?

I thought I read about criteria where the table should be smalller than depth and table should be less than 75%.....or something like that

You have already received good replies from SC and Yssie. Just to confirm, you mentioned AGA being the only one to grade cut, it is actually AGS, with AGA having also cut-grading-charts, based upon another approach.

I would however reconsider your strategy. Following these steps, you will likely end up with the cheapest or biggest stone matching your criteria, and passing the ASET as good enough. This might be your goal, no problem.

Another approach would be to contact the vendor, explain him or her what you want and let him give you options to choose from. Chances are that you will get a much better stone.

Live long,

I think this is how I would approach it.