Shallow crown and deep pavilion question

[Eugeniya]

Hi PSers!

I've learnt a lot through this wonderful forum during these couple of weeks. I'm still trying to understand relation between pavilion and crown angle in terms of optical performance, especially in the case of the lower crown angle and higher pavilion angle. I know about ideal proportions, but also wonder if there could be some exceptions. Our family friend (jeweller) sent me the GIA certificates for diamond studs (in martini setting), if I want to buy them. But I'm concerned about the large table, low crown and high pavilion angles. I cannot use HCA tool because I'm living in Myanmar (couldn't use Paypal). GIA report numbers: 6361542879 and 6351233053

Stone #1: 6361542879, 0.42 carat, J, VVS 2

PROPORTIONS​

Depth	60.3%
Table	62%
Crown Angle	33.0°
Crown Height	12.5%
Pavilion Angle	41.6°
Pavilion Depth	44.5%
Star Length	50%
Lower Half	75%

Stone #2: 6351233053, 0.41 carat, J, VVS 1

PROPORTIONS​

Depth	60.8%
Table	62%
Crown Angle	33.0°
Crown Height	12.5%
Pavilion Angle	41.6°
Pavilion Depth	44.0%
Star Length	50%
Lower Half	80%

I've seen the post by @Garry H (Cut Nut) about combination of lower crown angle with slightly deeper pavilion in this thread https://www.pricescope.com/communit...nd-pavilion-relationship.254253/#post-4668269 , but in my case proportions are at extreme..

Are these stones really duds in terms of light leakage/overall performance? I haven't seen them in person yet but tomorrow will look at them and compare with my studs with the same carat weight but better proportions.
Dear PS members, I would very appreciate you opinion about these stones, I'm a total newbie and just overwhelmed by all of these aspects of proportions and diamond performance..

 

[whitewave]

Garry does have some posts you might try to find where he specifically discusses earrings and how you can get away with looser parameters and a larger table since they aren’t right there on your ring finger.

My first question is: can you see these in person and what is the return policy?

 

[Eugeniya]

Garry does have some posts you might try to find where he specifically discusses earrings and how you can get away with looser parameters and a larger table since they aren’t right there on your ring finger.

My first question is: can you see these in person and what is the return policy?

Thank you for the advice! I will search for Gary’s posts about earrings with a larger table.
Actually the jeweller is our friend so I could take these earrings for several days and decide if I like them. I will get them next week (thought that tomorrow but plans changed). I also want to compare them to my current studs with the same ct weight but better proportions and see if they have a difference in performance. I’ve attached GIA for my current studs, one scored HCA between 1 and 2 and the second- about 2.6 (don’t remember clearly)

 

[lovedogs]

I typically tell people to avoid any stones where the table is larger than the depth. The stones will have a flat/pancake look and likely leakage

 

[Eugeniya]

I typically tell people to avoid any stones where the table is larger than the depth. The stones will have a flat/pancake look and likely leakage

thank you for the response! I see a slight difference between my studs - the center of one diamond with table 61%/depth 60.2% is slightly darker than the other with table 57%/depth 62.6%. Is it leakage? The difference is very subtle and I could see it only by close comparison of these diamonds side by side. I haven’t seen two diamonds with tables 62% yet so I don’t know how they would look

 

[Karl_K]

Reasonably bright but reduced contrast which in the ear is not a huge factor because of the longer viewing distance.
The biggest downsides are color retention, under table leakage, and lack of scintillation/life and fire.
I would not spend my own money on stones like those.

 

[Eugeniya]

Reasonably bright but reduced contrast which in the ear is not a huge factor because of the longer viewing distance.
The biggest downsides are color retention, under table leakage, and lack of scintillation/life and fire.
I would not spend my own money on stones like those.

Karl, thank you for the reply! Could you clarify do you mean those diamonds with 62% table? I also don’t understand what color retention is (I’m sorry, I started reading about diamonds just a month ago). I see a lot of fire in my current studs with tables 61% and 57%, but their pavilion/crown angles are 35/40.8 and 36/40.6 respectively. Fire and scintillation are the most important factors for me..

 

[Eugeniya]

What’s quite strange is that all of the mentioned diamonds were graded as triple excellent by GIA the jeweller told me that her criteria for selecting diamonds was triple Ex

 

[sledge]

What’s quite strange is that all of the mentioned diamonds were graded as triple excellent by GIA the jeweller told me that her criteria for selecting diamonds was triple Ex

Not strange at all. Most 3X stones aren’t all that excellent at all. Your jeweler is a noob if that is her defining criteria.

The problem is GIA has has too broad of definition for 3X cert. Factor in the averaging and rounding of values on the lab report they utilize and it just adds insult to injury.

Seriously fire her. Let the crew here help. What is your criteria and budget? US based or international?

 

[Karl_K]

Karl, thank you for the reply! Could you clarify do you mean those diamonds with 62% table? I also don’t understand what color retention is (I’m sorry, I started reading about diamonds just a month ago). I see a lot of fire in my current studs with tables 61% and 57%, but their pavilion/crown angles are 35/40.8 and 36/40.6 respectively. Fire and scintillation are the most important factors for me..

Color retention means they show more color than a better cut stone having the same material color.
Yes 62 tables are huge and 12.5 crown height is really low but if the pavilion angle was 40.8 or 40.6 like your others they would be much better than they are now.

 

[Eugeniya]

Not strange at all. Most 3X stones aren’t all that excellent at all. Your jeweler is a noob if that is her defining criteria.

The problem is GIA has has too broad of definition for 3X cert. Factor in the averaging and rounding of values on the lab report they utilize and it just adds insult to injury.

Seriously fire her. Let the crew here help. What is your criteria and budget? US based or international?

Thank you! I should give a bit of my background. I’m living in Myanmar and never shopped for anything with diamonds before - only for local CS like rubies or sapphire. Diamond jewellery is not available in the most of stores here (and often people here just selling bulky gold jewelry with melee for outrageous prices). The jeweller is our family friend and I wanted to get my first diamond studs. So I’ve asked her what she currently has in my budget (about 2500-2700 USD). She brought me the first pair of studs 0.85 cttw with jackets. Then I started searching web for the info about diamonds and found PS. I’ve used HCA tool to check my studs and scores were between 1 and 2 for one diamond and about 2.6 for another. These diamonds were in illusion setting (I’ve posted photos in my first thread here). I also wanted to have a look on another studs in martini setting that she had. I’ve asked her to send me GIA reports to check the proportions - and these were the stones mentioned in this thread with tables 62%.
Currently I have no option to buy from international vendors because of very high Myanmar customs fee for jewellery (30%) and high actual bank currency conversion rate for online transactions (it’s 1.5 higher than official rate). So the total price for jewellery would be almost 2 times higher if I will buy online internationally.
I want to get bigger diamond studs in the maybe next few years and plan to ask the jeweller to buy the stones for me within preferable proportions

 

[Garry H (Cut Nut)]

The 41.6 (too deep) and one with 75% lower halfs worry me the most.
It is a fact that shallower diamonds work best but that table size is also too big for my liking.
The left side of the chart at top of the page here are my recommendations. You can go a tad lower on the crown and pavilion angles too.

 

[Garry H (Cut Nut)]

Dirty Diamond Experiment
I did a shallow diamond earring test to prove the point for Peter Yantzer, then the Director of the AGS lab. We had debated shallow cuts and viewing distances for years, as discussed in earlier chapters. In 2005, I replaced one of my wife's earring ideal cut stones with a shallow diamond. The shallow stone had a 59.5% table, 31.3° crown and 40.6° pavilion with not very good symmetry. The remaining ideal cut stone had a 55.3% table, 34.9° crown and 40.75° pavilion with perfect optical symmetry (hearts and arrows).

After 3 months of annoying many people by asking which looked better, there was no doubt that the shallow stone performed better in all sorts of lighting environments. Clean or dirty. I had my wife swap ears with the diamonds every day to ensure they were equally dirty. That was when I discovered that shallow diamonds lose less brilliance when dirty. Peter Yantzer preferred the dirty shallow diamond earring when we were out to dinner at the JCK Las Vegas trade fair, much to his surprise.

 

[Eugeniya]

Color retention means they show more color than a better cut stone having the same material color.
Yes 62 tables are huge and 12.5 crown height is really low but if the pavilion angle was 40.8 or 40.6 like your others they would be much better than they are now.

Karl, thank you very much for clarifying! I’m a big intrigued to see them in person and compare to my current studs side by side

 

[Eugeniya]

The 41.6 (too deep) and one with 75% lower halfs worry me the most.
It is a fact that shallower diamonds work best but that table size is also too big for my liking.
The left side of the chart at top of the page here are my recommendations. You can go a tad lower on the crown and pavilion angles too.

Garry, thanks a lot for your response! Yes, almost all of the proportions of these stones are off and I’ve just wondered if they could somehow “work” together.
Do you mean this chart? Maybe I misunderstood where it’s located.
Post in thread 'Pricescope recommended proportions & the Inverse Crown and Pavilion Relationship'
https://www.pricescope.com/communit...and-pavilion-relationship.254253/post-4669155

 

[Garry H (Cut Nut)]

this is the chart - sorry, didnt paste the link

Diamond Proportions

The physics of light-behavior within a diamond are reliably consistent, which means proportions measurements can be useful.

www.pricescope.com

 

[Eugeniya]

this is the chart - sorry, didnt paste the link

Diamond Proportions

The physics of light-behavior within a diamond are reliably consistent, which means proportions measurements can be useful.

www.pricescope.com

Garry, thank you for the information! So these stones could be suitable for earrings if the table was a bit smaller (61%) with lower pavilion angle. My current studs are falling into “All around” and “Firey balanced” range so they look smaller and less bright but I’m a fan of fire

 

[Garry H (Cut Nut)]

Garry, thank you for the information! So these stones could be suitable for earrings if the table was a bit smaller (61%) with lower pavilion angle. My current studs are falling into “All around” and “Firey balanced” range so they look smaller and less bright but I’m a fan of fire

The trouble is there is very little fire seen in diamond studs when they are being worn.
And the dirt grease etc has a far more pronounced impact.

 

[Garry H (Cut Nut)]

 

[Eugeniya]

Wow, such a dramatic difference!
I keep these studs clean and I usually see fire while looking in mirror (from some distance also), but possibly it’s just a trick of my vision they also G color so looks quite bright.
I’m sorry for the photos quality, one in natural light and one in luminescent lighting

 

[Garry H (Cut Nut)]

Wow, such a dramatic difference!
I keep these studs clean and I usually see fire while looking in mirror (from some distance also), but possibly it’s just a trick of my vision they also G color so looks quite bright.
I’m sorry for the photos quality, one in natural light and one in luminescent lighting

The light near the mirror is the trick I suspect

 

[Eugeniya]

The light near the mirror is the trick I suspect

Maybe! But I also saw it in handheld mirror while moving through the room I’ve just been curious about fire in different light so checked it in different places and under different lighting settings at home. I rarely see fire in overcast daylight though.
It will be interesting to compare with these large table studs when I’ll get them to look at.

 

[Garry H (Cut Nut)]

Spot lights create fire.
But fire is hard to see from further away because the fans of dispersion are easier to miss.
This is a tolkowsky Ideal cut from 3M away with the light source coming from ceiling lights further away. The further you are away the less chance of seeing fire (or bright white sparkles). (57% 34.5 crown angle 40.75 pavilion angle)


And the same stone from 60cm away (2ft)


And now with the pavilion made 0.5 degree shallower (40.25) The entire stone comes to life. Compare the first and third images.

 

[Eugeniya]

Spot lights create fire.
But fire is hard to see from further away because the fans of dispersion are easier to miss.
This is a tolkowsky Ideal cut from 3M away with the light source coming from ceiling lights further away. The further you are away the less chance of seeing fire (or bright white sparkles). (57% 34.5 crown angle 40.75 pavilion angle)


And the same stone from 60cm away (2ft)


And now with the pavilion made 0.5 degree shallower (40.25) The entire stone comes to life. Compare the first and third images.

Garry, thank you so much for the explanation! In future I will try to get the shallower stones in my hand to try them as earrings. I assume that aforementioned stones with table 62% and pavilion 41.6% just won’t work in that way..

 

[Garry H (Cut Nut)]

Even worsa or worstestest. The proportions from above

 

[Eugeniya]

Even worsa or worstestest. The proportions from above

Yes, I’m completely agree! Thanks a lot for taking the time to explain it!

 

[Garry H (Cut Nut)]

Your welcome. Hope it was able to be understood. You asked great questions