Concerns about steep crown angle - princess cut

[diamond_guy123]

Hello,

So I just bought a princess cut diamond (have not received it yet). This could just be buyers remorse, or I'm just a guy that worries too much (probably the latter ). Here is the diamond: https://www.jamesallen.com/loose-diamonds/princess-cut/1.11-carat-i-color-vs1-clarity-sku-2071678 . I bought this diamond with the intention to return it if I was not satisfied.

Anyways, the 360 video looks great to me. There are 4 chevrons and I really like the look and performance. I would be interested to hear what others thought based on the specs and video.

What concerns me right now is the crown angle. The crown angle is 48.02 degrees with a pavilion angle of 38.40. Although this is described as an ideal cut diamond, it seems that no site which describes ideal cut diamonds even has this angle on its scale. Should I be concerned? Do you think this will greatly affect brilliance? Again, based on the video, I am impressed.

As a topic off of that question, I am wondering what people thought of "Ideal"" diamonds on James Allen which are not "Hearts & Arrows"? There is obviously no GIA grading scale, so it would seem that they would make as many cuts as possible "Ideal" as it allows them to increase the price. Do you all trust the cut grades on JA?

Thanks!

 

[John P]

Proportions ranges only apply to rounds. Princess cuts and other fancy shapes have too many variables to make performance judgments based on numbers. For example, while the main PA average is listed as 48.02 there are 5 more tiers of pavilion facets which are completely unreported. It would do no good to have that data anyway, because there is so much variability possible inside the averages. This is the reason the GIA Report only gives table & depth % and doesn't give a cut grade for the Princess shape: Too many variables to make any performance judgment based on numbers.

 

[diamond_guy123]

Thank you for your response. I find it interesting that some sites put out numbers for princess cuts nonetheless. Based on the JA video, what do you think of the performance of this particular diamond? Would you say an "Ideal" rating is justified?

 

[John P]

Thank you for your response. I find it interesting that some sites put out numbers for princess cuts nonetheless.

You're welcome. Those lists might be well-intended but simple geometry precludes them from being useful. Just consider; princess cuts come in 2, 3, 4 and 5 chevron configurations. That means some princess cuts only have 24 pavilion facets, others will have 48 and yet others fall in-between. Suggesting an ideal range for "pavilion angle" - which only relates to 4 of those facets - ignores many thousands of variables. This becomes exaggerated when you consider that the 20-44 unaccounted-for facets are often used to create "bulge," adding extra carat weight in the belly and creating light loss through the pavilion. Producers are not penalized for this since GIA doesn't apply a cut grade.

Based on the JA video, what do you think of the performance of this particular diamond? Would you say an "Ideal" rating is justified?

I'm in the trade so I cannot promote or condemn specific stones. I can say that the video is well-done, but you should know that a video isn't a performance indicator. As for the ideal-label, just talk to your contact at JA. I'm confident they'll explain what criteria this diamond meets to earn this designation.

 

[kenny]

FWIW, GIA does not grade the cut.
AGS does.

If light performance is your priority (it certainly would be mine) I'd look for a princess graded by AGS, and received their top grade of AGS 0.
Another approach is to buy a branded princess, like a Solasfera from Goodoldgold, or an ACA from Whiteflash.
I suspect those will be graded by AGS since it can justify a higher price.

 

[kenny]

Also, the ASET scope is a great cut evaluation tool.
http://ideal-scope.com/using-aset-scopes/

If you are not going to get an AGS 0 princess, I'd only get one graded by GIA if it performed well under the ASET scope ... but then the seller would have sent it to AGS to justify a higher price for it.

That's my understanding.