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Need help pick a stone! How much does a flat crown affect Princess cut?

JMowl

Rough_Rock
Joined
Sep 17, 2019
Messages
2
Hi All!
I'm new here - first time buying diamond for THE ring and friend recommended me here! I've been looking at Princess cut for few weeks now and finally narrow down to 2 options on James Allen:

Option 1:
CARAT: 2.02
MEASUREMENT: 7.02*6.96*5.02 (Ratio: 1.01)
COLOR: F
CLARITY: VS1
POLISH: Excellent
SYMMETRY: Excellent
TABLE: 71%
DEPTH: 72.1%
GIRDLE: Slightly Thick/Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/2.02-carat-f-color-vs1-clarity-sku-7244772

Option 2:
CARAT: 2.01
MEASUREMENT: 6.8*6.77*5.05 (Ratio: 1)
COLOR: F
CLARITY: VS2
POLISH: Excellent
SYMMETRY: Excellent
TABLE: 72%
DEPTH: 74.5%
GIRDLE: Very Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/2.01-carat-f-color-vs2-clarity-sku-7299903

So I asked the JA person for recommendation. The customer service was super nice, helped me to look at both diamonds, and told me both of them have too flat crowns.
Instead I picked a few more at similar price point, lower carats with better crowns.

Option 3:
CARAT: 1.82
MEASUREMENT: 6.67*6.58*4.75 (Ratio: 1.01)
COLOR: E
CLARITY: VVS2
POLISH: Excellent
SYMMETRY: Excellent
TABLE: 72%
DEPTH: 72.2%
GIRDLE: Medium/Slightly Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/1.82-carat-e-color-vvs2-clarity-sku-7714148

Option 4:
CARAT: 1.81
MEASUREMENT: 6.54*6.52*4.84 (Ratio: 1)
COLOR: E
CLARITY: VS1
POLISH: Excellent
SYMMETRY: Very Good
TABLE: 72%
DEPTH: 74.3%
GIRDLE: Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/1.81-carat-e-color-vs1-clarity-sku-624307

Option 5:
CARAT: 1.77
MEASUREMENT: 6.47*6.47*4.81 (Ratio: 1)
COLOR: F
CLARITY: VS1
POLISH: Very Good
SYMMETRY: Very Good
TABLE: 71%
DEPTH: 74.3%
GIRDLE: Thick/Very Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/1.77-carat-f-color-vs1-clarity-sku-5677283

Not that I don't trust the JA customer service, who was actually super nice and patient. I'd like to seek some second opinions from the experts... So are the flat crown of the first 2 options really bad? Which one should I pick? Open to any suggestions as well, thank you so much!
 
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mwilliamanderson

Shiny_Rock
Joined
Aug 13, 2013
Messages
199
Your friend did you a favor by steering you here! Have you read the article on Pricescope titled Princess Cut Grading? I’ve included some cut info from the article below. In general however I would lean toward stones with a thin to medium or medium to slightly thick girdle. Otherwise you are paying for weight that you can’t see and that doesn’t contribute to the diamond’s brilliance or fire. Hopefully those with specific Princess cut knowledge will contribute their thoughts about these specific stones. You would however, be better served to get certificates and Aset or IS images for each stone. This can be challenging with James Allen.


Generalizations about Ideal Princess Cuts
Some may find these “rules of thumb” about high performing princess cuts to be helpful, bearing in mind they are not hard and fast rules.



• The AGS grading system favors full crowns. It is difficult to achieve a 0 when the crown height is less than 12%. Fuller crowns help the princess cut produce more fire. The AGS System does not mandate fuller crowns to produce more fire. It’s just that better light performance mandates it.

• The AGS system favors smaller tables. It is very difficult to get a 0 with a table size of 69% or greater. Similar to above, too large a table reduces crown area and the light performance suffers.

• The total depth of most ideals falls between 74.0% to 77.0%. (However it is quite possible to achieve 0 outside this range.)

• As a general rule the table size should not exceed the depth percentage.

• The azimuth (index) of the star facet should differ by about 6 to 10 degrees from the azimuth of the corresponding crown facets. This results in a more “squarish” table. When the azimuth difference is large, say 18 or 20 degrees, the table appears more “angular” shape (think of an octagonal stop sign) and the light performance tends to suffer.

• The cut grade system favors pavilions with good facet definition between the pavilion facets, particularly between pavilion 1 and the chevron facets. When the triangular pavilion 1 facet is cut too shallow, then facet definition suffers and the pavilion appears “pointy” rather than full and slightly rounded.
 

mwilliamanderson

Shiny_Rock
Joined
Aug 13, 2013
Messages
199
Here are two stones which receive the highest AGS rating. I used parameters similar to yours to search for these.

https://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-4152284.htm
https://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-4133764.htm

Here are some in a similar price range to what you found. I believe most of us here would be comfortable recommending any of these!

https://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-4054982.htm
https://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-3891971.htm
 

JMowl

Rough_Rock
Joined
Sep 17, 2019
Messages
2
Thank you! So seems like princess cut with a flat crown is a no-go then..

Here are two stones which receive the highest AGS rating. I used parameters similar to yours to search for these.

https://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-4152284.htm
https://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-4133764.htm

Here are some in a similar price range to what you found. I believe most of us here would be comfortable recommending any of these!

https://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-4054982.htm
https://www.whiteflash.com/loose-diamonds/princess-cut-loose-diamond-3891971.htm
 

mwilliamanderson

Shiny_Rock
Joined
Aug 13, 2013
Messages
199
Thank you! So seems like princess cut with a flat crown is a no-go then..

For the best performance you want to stay within the following parameters OR buy an AGS000 stone.

Crown 12% or greater
Table 69% or less
Total depth between 74-77%
James Allen will provide certificates on request so you can check the dimensions for yourself.
 

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Rockdiamond

Ideal_Rock
Trade
Joined
Jan 7, 2009
Messages
7,689
Hi,
Welcome to Pricescope!
Princess cuts- and all fancy shapes-offer far more varieties than round diamonds in terms of cut.
Many lovely princess cuts fall outside the parameters of an "ideal" cut stone.
Yes, stones with high crowns can be lovely. But a flatter crown is not neccessary bad. Taste comes into play. Just as an example- princess stones that are a bit more shallow ( below 70% depth) can have a larger spread than "ideal" cut stones.
As a trades person I'm not allowed to comment on specific stones- my comments are general.
 

lovedogs

Ideal_Rock
Premium
Joined
Jul 31, 2014
Messages
9,365
I think princess cuts (like all "fancy" cuts), can't be purchased based on numbers alone. you really need to see how the stone performs in video/pics, etc, and use your preferences and advise from experts. Sadly it's not like rounds where there are strict parameters and stones that fall in them are likely to perform well and those that fall outside are likely to perform poorly.

As far as I know, WF is the only place to get "ideal" cut princess stones. So those will be the best cut available. But there are many other great ones and the fancy cut experts here can help you!
 

Rockdiamond

Ideal_Rock
Trade
Joined
Jan 7, 2009
Messages
7,689
So those will be the best cut available.
I can totally understand how you can get the impression that "ideal" as classified by AGS is the "best" cut......but the term "Ideal" is a commercial, as opposed to scientific.
Many experts will choose a stone not classified as "Ideal" by AGS to be a better cut than another which has been graded "Ideal" in a princess cut.
 

diamondhoarder

Shiny_Rock
Premium
Joined
Apr 5, 2012
Messages
471
Hi All!
I'm new here - first time buying diamond for THE ring and friend recommended me here! I've been looking at Princess cut for few weeks now and finally narrow down to 2 options on James Allen:

Option 1:
CARAT: 2.02
MEASUREMENT: 7.02*6.96*5.02 (Ratio: 1.01)
COLOR: F
CLARITY: VS1
POLISH: Excellent
SYMMETRY: Excellent
TABLE: 71%
DEPTH: 72.1%
GIRDLE: Slightly Thick/Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/2.02-carat-f-color-vs1-clarity-sku-7244772

Option 2:
CARAT: 2.01
MEASUREMENT: 6.8*6.77*5.05 (Ratio: 1)
COLOR: F
CLARITY: VS2
POLISH: Excellent
SYMMETRY: Excellent
TABLE: 72%
DEPTH: 74.5%
GIRDLE: Very Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/2.01-carat-f-color-vs2-clarity-sku-7299903

So I asked the JA person for recommendation. The customer service was super nice, helped me to look at both diamonds, and told me both of them have too flat crowns.
Instead I picked a few more at similar price point, lower carats with better crowns.

Option 3:
CARAT: 1.82
MEASUREMENT: 6.67*6.58*4.75 (Ratio: 1.01)
COLOR: E
CLARITY: VVS2
POLISH: Excellent
SYMMETRY: Excellent
TABLE: 72%
DEPTH: 72.2%
GIRDLE: Medium/Slightly Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/1.82-carat-e-color-vvs2-clarity-sku-7714148

Option 4:
CARAT: 1.81
MEASUREMENT: 6.54*6.52*4.84 (Ratio: 1)
COLOR: E
CLARITY: VS1
POLISH: Excellent
SYMMETRY: Very Good
TABLE: 72%
DEPTH: 74.3%
GIRDLE: Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/1.81-carat-e-color-vs1-clarity-sku-624307

Option 5:
CARAT: 1.77
MEASUREMENT: 6.47*6.47*4.81 (Ratio: 1)
COLOR: F
CLARITY: VS1
POLISH: Very Good
SYMMETRY: Very Good
TABLE: 71%
DEPTH: 74.3%
GIRDLE: Thick/Very Thick
https://www.jamesallen.com/loose-diamonds/princess-cut/1.77-carat-f-color-vs1-clarity-sku-5677283

Not that I don't trust the JA customer service, who was actually super nice and patient. I'd like to seek some second opinions from the experts... So are the flat crown of the first 2 options really bad? Which one should I pick? Open to any suggestions as well, thank you so much!
I am the owner of a "flat crown" princess. I don't know the crown height % but it has table 71% and depth of around 69%. Despite not following the official "rules" for princess cuts it has loads of fire and brilliance. Here are some photos:


20180226_122533 (2).jpg 20180226_122759 (2).jpg 20180226_122632.jpg

I have other stones which do fall within "ideal" parameters but this holds up very well against them. And the other great advantage with this stone is that it faces up big for a 2.1ct (7.25mm). Some of the ideal cuts with greater depth percentages face up quite a bit smaller. Also the facet patterns can be different to the more "traditional" look princess cuts like mine.

So my advice would be: go with what your eyes like and be prepared to scrutinise videos, ASET images and try to see some different "flavours" of princesses in person so you can decide what you prefer.

Of the JA options you posted I personally think that option 2 looks the brightest and has a pleasing facet pattern. But that's just my opinion. You need to go with what appeals to you the most.
 

Rockdiamond

Ideal_Rock
Trade
Joined
Jan 7, 2009
Messages
7,689
Some of the ideal cuts with greater depth percentages face up quite a bit smaller.
This!!!
For sure, Ideal Princess Cuts have a distinctive look- and they can be extremely bright.
But then again, so can a well-cut Princess cut with a flatter top! In general- an Ideal will have larger bright flashes while flatter top stones have less organized patterns of tiny sparkles.
If you're a person who prefers the type of sparkle a flatter top creates, it's possible you're going to get a better stone for the money in terms of color and clarity.
And a 2ct Ideal Princess may very well be noticeably smaller dimensionally than a flatter top stone of 2cts.
IMO, if they are both well-cut, Ideal and flatter top Princesses can both be valid choices.
The idea that the Ideal Princess is automatically "better" than one with a flatter top is simply not accurate- and could easily be ( unintentionally) misleading.
 

flyingpig

Ideal_Rock
Premium
Joined
Nov 7, 2015
Messages
2,010
I agree #2 has good light return. But that thick girdle and spread is unacceptable.
#4 looks good as well, though not the best.
 

Karl_K

Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
8,394
Princes cuts are weird, the crown has little effect face up one with a 99% table and no crown could be a "princess cut" that holds up with other well cut princess cuts face up.
Tilted the table does come into play more but not as much as one would expect.
So the answer to the question is very little with the right pavilion.
 

OoohShiny

Ideal_Rock
Premium
Joined
Apr 25, 2014
Messages
5,868
Princes cuts are weird, the crown has little effect face up one with a 99% table and no crown could be a "princess cut" that holds up with other well cut princess cuts face up.
Tilted the table does come into play more but not as much as one would expect.
So the answer to the question is very little with the right pavilion.
I don't understand how that works... :???: lol

Surely crown height / crown facet size plays a key role in determining dispersion in all cuts, because the physics remains the same?!
 

Karl_K

Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
8,394
I don't understand how that works... :???: lol

Surely crown height / crown facet size plays a key role in determining dispersion in all cuts, because the physics remains the same?!
The table is so large and the facets that are there are such a low angle its not a huge difference to having just a flat facet.
The "work" is done in the pavilion.
I cant find the dmc file where I optimized a no crown but even with no optimization you can get this:
With:
withcrown.jpg
Without:
withoutcrownfacets.jpg
This one is not that great but it gives the idea.
 

Rockdiamond

Ideal_Rock
Trade
Joined
Jan 7, 2009
Messages
7,689
Karl's example is extreme- but it does give you the idea.
Another aspect which seems to get ignored in such discussions is how the diamond grabs light from so many directions/sources- and as you move the diamond, different facets are grabbing the light.
It manifests itself in different size and number of flashes.
The "Brilliant" ( Ideal) style of cutting definitely does have larger flashes that are brighter individually- which is the "scientific" justification for saying it's a "better" cut.
Sure, there are horribly cut diamonds- but in reality, there's a wide range of different light performances that will be seen as "pretty" by a fair number of observers.
 
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