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Pricescope recommended proportions & the Inverse Crown and Pavilion Relationship

Karl_K

Ideal_Rock
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With a shallow 34 crown and shallow 40.6 pavilion I would anticipate you'd also have shallow depth.

My guess is these factors played together to create obstruction which made the stone look darker.
All depends on whats in the averages and the lowers.
But for any given distance a true 40.6 pavilion reacts to obstruction more than a true 40.8 pavilion and a 34 crown will showcase that a bit.
The difference is not night and day, its subtle.
Lower % number lowers also show obstruction more because they are bigger.
Without more info and viewing them side by side in the same conditions it is hard to say anything that is not just a wild guess.
 

Karl_K

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I said generic images, not images based on scans of the diamonds using the best scanner at a high resolution setting.

Those images can not be applied to a different diamond with the same numbers on the report.
 

AV_

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Outside Pricescope norms, I am seeing rounds with extreme spreads & priced accordingly [at times], with rather beautiful patterns of brilliance fondly recognized as historical styles of cut... The HCA kills them lot.
 

AV_

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Outside Pricescope norms, I am seeing rounds with extreme spreads & priced accordingly [at times], with rather beautiful patterns of brilliance fondly recognized as historical styles of cut... The HCA kills them lot.
 

Mlh

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All depends on whats in the averages and the lowers.
But for any given distance a true 40.6 pavilion reacts to obstruction more than a true 40.8 pavilion and a 34 crown will showcase that a bit.
The difference is not night and day, its subtle.
Lower % number lowers also show obstruction more because they are bigger.
Without more info and viewing them side by side in the same conditions it is hard to say anything that is not just a wild guess.
Thank you @Karl_K , and @sledge !!
 

Ceilimom

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Is it possible to get brillance, fire, scintillation in a higher colored stone( M-P)? I would love to upgrade my diamond ring to a 2.6 carat, nothing below VS1, prefer VVS1 or VVS2. Love to have Cushion Brilliant or MBR, any hopes to get wonderful sparkle and light return? No brown or grey, a soft yellow is my aim?
 

coda72

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Is it possible to get brillance, fire, scintillation in a higher colored stone( M-P)? I would love to upgrade my diamond ring to a 2.6 carat, nothing below VS1, prefer VVS1 or VVS2. Love to have Cushion Brilliant or MBR, any hopes to get wonderful sparkle and light return? No brown or grey, a soft yellow is my aim?
Here’s one that you may like. Not sure what your budget is though.

 

Ceilimom

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Here’s one that you may like. Not sure what your budget is though.

I really appreciate the suggestion and if this was another vendor I would reach out to them.I had the worst experience with Brian Gavin sales staff, the worst customer service experience on an epic level.
 

Mlh

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What does a big white area on the rim of hearts and arrows image mean? Just browsing and saw that on one.
 
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AV_

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The Shallow diamonds could have high Light return but it have weak " Life."
Deep diamonds could have less Light return, but much bigger and attractive "Liffe"
I could point at a pair of stones, listed today, that show this perfectly - both very beautiful [LGF 85%, LGF 70%; the flat resembles the model mentioned by @Garry H (Cut Nut) in the #24th post;] prices reflect the spreads.

The HCA is too narrow-minded for these options. I am not. There are many more types with a following, even just of RBC.

The H&A is even more narrow-minded - but has a point to make beyond proportions, of precission that is a pleasure understood beyond diamonds.

RBC is also narrow-minded, if such a large domain of possibilities.

...
 

AV_

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What does a big white area on the rim of hearts and arrows image mean? Just browsing and saw that on one.
This would be easy to answer using ray tracing & not easy off the cuff! I guess that the stone has a wide, possibly also uneven girdle, that is responsible for extra secondary reflections exactly everywhere throughout the H&A pattern.
 

Mlh

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This would be easy to answer using ray tracing & not easy off the cuff! I guess that the stone has a wide, possibly also uneven girdle, that is responsible for extra secondary reflections exactly everywhere throughout the H&A pattern.
Wow. Interesting!! Thanks @AV_!
 

Serg

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Sergey how far along the sweet ling would you go in each direction?
Many PS people recomend up to 36 crown with 40.5 pavilion. I agree. What people have not been recommending is deeper pavilion shallower crowns. I like down to 41.3/32.
Garry, I am in Surat now and I have compared today in different illuminations ( Outdoor, Lexus Office, Fire and DiboxJD) MSS13, MSS16, MSS17, MSS18

even MSS17 with P40 Cr39 looks fine for me( at least it is better than some Shallow 3EX diamonds with P 40.6 and Cr 34) .
Screenshot 2020-01-30 17.38.12.png
 

Serg

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DiboxJD movies


- MSS13 Ca 34, Pa 41, Tb 57,
- MSS16 Ca 37.5, Pa 40.6, Tb 57,
- MSS17 Ca 39, Pa 40, Tb 61,
- MSS18 Ca 37.5, Pa 40.4, Tb 57
 

Mlh

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DiboxJD movies


- MSS13 Ca 34, Pa 41, Tb 57,
- MSS16 Ca 37.5, Pa 40.6, Tb 57,
- MSS17 Ca 39, Pa 40, Tb 61,
- MSS18 Ca 37.5, Pa 40.4, Tb 57
Wow! The 37.5 ca are beautiful! Why do ideals never include these combos on PS?
 

prs

Brilliant_Rock
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We have an informal group-think proportion recommendation often quoted to advise newbies on what to look for. I would like to discuss and consider widening that cut range in this thread.

  • Most people have a budget, it might be $2,000 or $200,000. Often you do not know until they ask about a specific diamond. But for everyone who posts a question there might be dozens of live readers or lurkers and 100’s or 1,000’s who find a discussion and are influenced by it..
  • We advise on color and clarity too, for example many people start out higher in clarity and we often bring them back to VS/SI1. Often F, G, H are safe cost effective color recommendations. Widening their cut criteria can help them heaps.
  • The cut ranges we recommend tend to be tight and INHO will pass over many ‘good enough’ diamonds. Remember you all may be helping a newbie but don’t forget the lurkers who may have other agendas - must be one carat for <$4k etc and they might be too embarrassed to post.
I have been the ‘CutNut’ since the mid 1990’s when I knocked on Martin Rapaport’s door of his NYC office. I introduced myself as a diamond cut nerd; he flicked me a few diamonds and asked me to loupe them and tell him table size, crown and pavilion angles etc. After 3 or 4 stones he gave me my handle. In 1999 at his annual talk in Vegas he told the retail trade “if you aren’t adding value to the diamonds you sell you might as well be flippin hamburgers”. He showed a slide of Pricescope and said most retailers will disappear. I contacted the PS founder, Leonid, and offered to write a tutorial for the site. Rest is history.

My PS involvement has been based on helping people get better looking more beautiful diamonds buy learning and making life difficult for the dinosaur wholesale and cutter trade, who mostly still today flip diamonds. Today I get some criticism from elitist consumers and vendors who believe that everyone should buy the very best cut. And I agree, but realistically there are so many variables and unknowable’s that the average Jo/sephine is totally overwhelmed; most want a good enough or better diamond. My strongly held belief is that if I can help people get a better bigger looking diamond for their $$’s then a fair % will ‘get it’ – that is they will understand what we bang on about.

If their diamond gets more accolades than other peoples then there is a chance that we will convert some of them into addicts who will become one of you. And so many of you have become Supa Dupa Ideal Cut junkies. And that is fantastic because you really ‘get it’. Cut is King or Queen.

So the purpose of this discussion is to see if we can not widen the scope of our cut recommendations.

Maybe it can have a Good, Better and Best range? Supa Dupa being the very bestest.
Garry, I've been thinking about this a lot and I've come to the conclusion almost all of us don't see enough diamonds to be able to offer informed opinions as to what the "Good, Better and Best" ranges might be. I personally don't know if light performance slowly degrades as cut proportions increasingly deviates from ideal, or if light performance falls off a cliff as soon as there is any significant deviation from ideal. As of now the HCA seems to say that light performance falls of a cliff. Any diamond with an HCA below 2.0 is a potential buy, and any diamond above 2.0 is not. Garry, I don't know if this is your intent but that's how it is being taken.

If light performance does slowly degrade then it should be possible to define cut proportions into categories. Starting with an "Ideal" proportions category that gives 95-100% of super ideal, maybe a "Superior" category includes diamonds that would give 90-95% light performance, and a "Satisfactory" category that gives 85-90%. I'm pulling these numbers out of my hat, and only trade members who see all types of diamonds every day would have the expertise to define these cut categories. Maybe a committee of Garry, Sergey, and Karl could do it?
 

Rockdiamond

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I personally don't know if light performance slowly degrades
This is a great question that spurs many more.
For example, is "light performance" linear?
Of course, it's not! It's a matter of taste.
So what one person feels is the best light performance, is not necessarily what the next person will see as best.
 

AV_

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@prs @Rockdiamond I remember charts showing values of the HCA metric over a larger range of proportions that answer this, up to perception.

I've always thought that the glory of the brilliant cut is that it makes sharp variations impossible [or close enough for my back of the envelope remarc] for its inherent constraints to relative facet positions; step cuts, do not. [I am often wrong. @diagem]

I love the letter, of course, possibly because the contrast possible, 'Life' as @Serg calls it [OK, of course not, but they look the part to me]
 
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Serg

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Garry, I've been thinking about this a lot and I've come to the conclusion almost all of us don't see enough diamonds to be able to offer informed opinions as to what the "Good, Better and Best" ranges might be. I personally don't know if light performance slowly degrades as cut proportions increasingly deviates from ideal, or if light performance falls off a cliff as soon as there is any significant deviation from ideal. As of now the HCA seems to say that light performance falls of a cliff. Any diamond with an HCA below 2.0 is a potential buy, and any diamond above 2.0 is not. Garry, I don't know if this is your intent but that's how it is being taken.

If light performance does slowly degrade then it should be possible to define cut proportions into categories. Starting with an "Ideal" proportions category that gives 95-100% of super ideal, maybe a "Superior" category includes diamonds that would give 90-95% light performance, and a "Satisfactory" category that gives 85-90%. I'm pulling these numbers out of my hat, and only trade members who see all types of diamonds every day would have the expertise to define these cut categories. Maybe a committee of Garry, Sergey, and Karl could do it?
If it is a cliff then it is a cliff from one side only( shallow diamonds)
it is not a cliff in direction to deep pavilion diamonds .

it is more looks as mountain range in Sweetline direction with many different and nice pikes depends from LGF, table , star, painting variations.
Also you may find other type of beauty in steep /deep direction Screenshot 2020-02-05 12.24.47.png
 

sledge

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While we may have our own yellow with pink polka dots attraction, that doesn't necessarily mean it's a good general guideline for recommendation.

For instance in the video @Serg posted I am particularly fond of MSS16. The 61% LGF's are stupid fat and remind me of those big chunky facets I adore in OEC's.


While beautiful to me, it is very much an outlier compared to a traditional MRB. All the things I like about this stone are things my wife would dislike (who doesn't appreciate OEC's the way I do).

Also you have to factor in the oddities of GIA rounding and averaging. The stones in the master list have the luxury of more precise measurement.

So keeping a set of recommendations tight help alleviate some concern of said recommendation having actual values that may produce a result that is different than originally intended.

Photo_16_large.jpg
 

Karl_K

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Here is an issue outside the hca ranges and outside the ideal cut diamond chart ranges there are great proportions but they are more of a shotgun pattern rather than large groupings.

At one time aprox 40/40 in an oec style was consider an excellent cut.
I say approximately because the measuring tools of the day were not that accurate.
I have been playing with them in virtual and there are some very good combos there both with oec and more modern lowers.
With 40% stars mss17 would score higher and look better because in the video and aset you can see the results of the over steep uppers.
Lengthening the uppers so they are at a shallower angle would help.
 
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Karl_K

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MSS16 also shows over steep uppers(blue arrows point to a few of them) moving the stars% from the green arrow to the red would help and likely fix the issue.
Back in the day a star% of 35%-40% was not that uncommon for this very reason.
Photo_16_large.jpg
 

Rockdiamond

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While beautiful to me, it is very much an outlier compared to a traditional MRB.
This is a great point- and central to many discussions about cut.
My position is that there's no single "right" or "best" way to cut a modern RBC.
But Sledge's point is a good one- some people expect a diamond to look a certain way.
I think where the disagreements lie is exactly how to advise newcomers on what to look for.
If one expects to see H&A ( for example) any stone not exhibiting them won't look "right.

To Serg's point about a cliff....
I agree it's virtually impossible to cut a "regular" RBC shallower than about 57% without severe visual penalties- such as "Fish Eye" ( while the deep ones won't necessarily have easily noticeable deficiencies)
BUT- as Karl is pointing out- there's plenty of amazing designs that can stand up to a super shallow depth and still look amazing. The danger is for folks to assume that what's true for a modern RBC is also true for other shapes.
 
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prs

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@Rockdiamond The problem with your position here is the same as it was when I asked you for details on the great looking 60/60 diamonds of your youth. You have all the experience required to know a great looking stone when you see one. You also get to see lots of diamonds so you can just pick the ones that look best to you. There is no need for you to be concerned about all those fussy cut proportions! :)

We consumers don't get to see lots of diamonds in person, and we sure don't get to compare lots of diamonds side by side in order to learn how to pick out the best ones. In order to buy on-line consumers have to know what cut proportions have the potential to yield the best looking diamonds. How else can they wade thru the ocean of diamonds out there?

If I read your posts correctly you are saying do away with the HCA system entirely and just go by eye. I don't find that position helpful at all...my eye ain't that good! :mrgreen2:
 

Rockdiamond

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HI Peter,
My position is not to do away with HCA- not at all!
And I completely get what you're saying about wanting to have all the info as a consumer!
But there are aspects of cut and beauty that are not possible to chart numerically.
Personally, I would prefer to buy specialty items from experts who can vet them for me.
But today's diamond market is primarily data-driven - based on buying from a list of candidates.
I have never had the mentality to become a stat monger when it comes to what I love in diamonds....you're right, I use my eyes, and the tonnage of diamonds available for us to inspect personally.
That's the main reason I don't have "perfect" 60/60 numbers to share- and also why I like HCA, for when a PS client asks about it.
But it's kind of moot for me, as a seller.
As a forum member with my life experience, I do feel that newcomers are very forcefully pushed in one specific direction, and not the one I would.
 
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Karl_K

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David we have had this conversation before but there are some that haven't heard it.
The problem with I know it when I see it if given an identical pile of say 100 diamonds and say pick your top 10.
While there would be some overlap overall the mix would be very different if You, Garry, Serg, Sir John, and I were picking out our top 10.
That does little to help someone else remotely finding a diamond.
 

sledge

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David we have had this conversation before but there are some that haven't heard it.
The problem with I know it when I see it if given an identical pile of say 100 diamonds and say pick your top 10.
While there would be some overlap overall the mix would be very different if You, Garry, Serg, Sir John, and I were picking out our top 10.
That does little to help someone else remotely finding a diamond.
Yes and no.

Karl = Green
Serg = Red
Garry = Blue

As you can see, the vast majority of each respective color does NOT overlap. However, the parts that overlap is the criteria that would be most useful to a GENERAL population.

More specifically, maybe the white area is the most universal and what I'd envision as the criteria currently being provided (34-35 crown, 40.6-40.9 pavilion, etc, etc). It's safe.

The light blue, yellow & pink areas might be "extended criteria" where you get some unique combos that fall outside the most common white area, but still gets consensus of being acceptable.

1580946046512.png
 

prs

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Yes and no.

Karl = Green
Serg = Red
Garry = Blue

As you can see, the vast majority of each respective color does NOT overlap. However, the parts that overlap is the criteria that would be most useful to a GENERAL population.

More specifically, maybe the white area is the most universal and what I'd envision as the criteria currently being provided (34-35 crown, 40.6-40.9 pavilion, etc, etc). It's safe.

The light blue, yellow & pink areas might be "extended criteria" where you get some unique combos that fall outside the most common white area, but still gets consensus of being acceptable.

1580946046512.png
Terrific drawing Sledge, but I suspect with Serg, Karl, and Garry there would be a heck of a lot more overlap, and the white area would be much bigger.

However if David were added to the group we would find lots of sky blue pink little balls covered in yellow dots lying well outside the lines. :lol-2:
 
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