What are your dream proportions?

[chamois]

For table/crown/pav/depth/lgf etc.?

 

[AV_]

Lgf 60 - 70% ; I have not worked out proportion ranges; the HCA may still work for 70% which is done in deeper modern brilliants.

I have a couple of MRB types on my list, that are outside H&A by some distance. Within H&A the same flavours are still recognizable, but very mild.

 

[sledge]

Lgf 60 - 70% ; I have not worked out proportion ranges; the HCA may still work for 70% which is done in deeper modern brilliants.

Theoretically, the LGF's alone would have zero bearing on the HCA score. Minor facets such as stars and LGF's are not input into the HCA analysis.

Did you see this?

57.2 table, 61.9 depth, 37.3 crown, 40.6 pavilion & 62 LGF's

More images and specs on MSS16:

OctoNus : Master Stone Set - diamond 16

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

 

[diamondsR4eVR]

What’s lgf?

 

[sledge]

What’s lgf?

LGF = lower girdle facets

Round Cut Diamond in Detail

Modern round brilliant cut diamonds are composed of flat polished surfaces called facets. Learn more about this popular diamond shape here.

www.pricescope.com

 

[Dreamer_D]

Lgf 60 - 70% ; I have not worked out proportion ranges...

Here it is! Depth is only about 56%, table ~50%. Don't know the pavilion and crown angles though.

 

[sledge]

Here it is! Depth is only about 56%, table ~50%. Don't know the pavilion and crown angles though.

Is this an MRB or OEC?

Feel like I'm missing part of a story line....lol

 

[Dreamer_D]

Is this an MRB or OEC?

Feel like I'm missing part of a story line....lol

This is my Early Ideal cut, it's about 100 years old. You need to read your PS history for the storyline...

 

[Dreamer_D]

Did you see this?

57.2 table, 61.9 depth, 37.3 crown, 40.6 pavilion & 62 LGF's

This is funny to see, as this is basically what my antique diamond looks like, but mine has a smaller table and it is shallower and the LGFs may be a little longer. The video is very true to what my diamond looks like in real life.

 

[Dancing Fire]

@cflutist 2.18ct E VS1...

 

[AV_]

This [Octonus sample] is funny to see, as this is basically what my antique diamond looks like, but mine has a smaller table and it is shallower and the LGFs may be a little longer.

There is a relationship like that - lgf, depth etc. that predicts types & patterns of brilliance over the historical forms of the round brilliant, not just the MRB. I rather want to have fun with it and ETAS (have started a thread to remind myself of the task, not that I need reminding, since I seem to keep gettng back to this forum every day or so)

Your diamond is such a rarity! I keep seeing the shortish Lgf in MRB cut around 65% depth, unremarcable table % - up to 60-61. Low depth certainly makes LGF more prominent; the relatively shallow MRB tend to have them so long - 80%! to accomodate larger tables turning those facets mirror/dark. MRB variations, I know I am drawn to the ones with too much contrast [playing with those dark facets is amusing, although the look of the stones standing still, is iffy]

ramble

 

[Garry H (Cut Nut)]

Table size and LGF are rellated and need to be accounted for.

This chart predates GIAs cut grading system of 2006 and so uses LGF length which is about 2% longer than GIA's LGF depth measuement.

 

[Karl_K]

Table size and LGF are rellated and need to be accounted for.

This chart predates GIAs cut grading system of 2006 and so uses LGF length which is about 2% longer than GIA's LGF depth measuement.

Honestly I do not agree with that chart.
There are many possible different looks with various table sizes/lgf%/and proportions that to declare one the very best seems very wrong to me.
Which is why I do not agree that the modern tolk super-ideals and tolk equivalent super-ideals are the kings of round diamonds some of them are great but so are possibly many others.

To answer the question there are many different combinations of proportions that I would love to have and many of them would look and have a personality substantially different from one another accross a wide range of lighting.

 

[Karl_K]

Lets take AGSL LP grading to step on a sacred cow.
They took a known good range and using their technology assigned numbers to different properties they defined.
Then they set a range for each of those properties and set out to find similar proprieties in different combinations that are "like" their chosen range and called them ideal.

That does not mean that all other combinations of that criteria is bad they are just not "like" their ideal.
There are some however that do not meet their criteria which could indeed be considered not that great.
So its a system that works on some levels to sort diamonds into a group.
But the sorting is not bad or good its "like" or "not like".
You know one of these things is not like the others......

 

[sledge]

How's those 60% LGF's work for you @Karl_K that I posted earlier in the OctoNus sample set?

Just razzing you. I know you tend to like the 80+ LGF's.

Definitely a preference thing.

 

[Karl_K]

How's those 60% LGF's work for you @Karl_K that I posted earlier in the OctoNus sample set?

Just razzing you. I know you tend to like the 80+ LGF's.

Definitely a preference thing.

I love it.
I like short lgf% and oec style stones a lot.
If I could change one thing on it that would be a ~55% table to raise the ch% and adjust as needed.

 

[Karl_K]

I know you tend to like the 80+ LGF's.

I like long lgf% when they make sense and with some combos.
What I object to is the notion that there is anything magical about any particular lgf% number.

 

[Garry H (Cut Nut)]

Honestly I do not agree with that chart.
There are many possible different looks with various table sizes/lgf%/and proportions that to declare one the very best seems very wrong to me.
Which is why I do not agree that the modern tolk super-ideals and tolk equivalent super-ideals are the kings of round diamonds some of them are great but so are possibly many others.

To answer the question there are many different combinations of proportions that I would love to have and many of them would look and have a personality substantially different from one another accross a wide range of lighting.

Karl I simply point out that no one ever noticed the relationship between table size and LGF's.

What ever your preference might be, then you simply can adjust LGF's up or down for a range of prospective table sizes.
The same can also be said for pavilion angles - for example for nice shallow pavilion and steeper crown angles the LGF's need to become longer or otherwise the table area becomes dark.

 

[Mlh]

Karl I simply point out that no one ever noticed the relationship between table size and LGF's.

What ever your preference might be, then you simply can adjust LGF's up or down for a range of prospective table sizes.
The same can also be said for pavilion angles - for example for nice shallow pavilion and steeper crown angles the LGF's need to become longer or otherwise the table area becomes dark.

@Garry H (Cut Nut) , are you saying that a 35 crown, 40.6 combination for instance, would be less likely to have darkness issues with 80% lgf vs 75%lgf?

 

[sledge]

@Garry H (Cut Nut) , are you saying that a 35 crown, 40.6 combination for instance, would be less likely to have darkness issues with 80% lgf vs 75%lgf?

Seems like a simple question, but it's a little more complicated as you have to consider those are likely GIA reported values.

Why does it matter?

GIA reported 75 = varies from 73-77 actual
GIA reported 80 = varies from 78-82 actual

Likely the same result if you have actuals of 77-78 which would show up as 75 or 80. However, the effect could be different if actuals were 73 and 82. Yet both would again show up as 75 and 80 on the lab report.

Make sense?

 

[Mlh]

Seems like a simple question, but it's a little more complicated as you have to consider those are likely GIA reported values.

Why does it matter?

GIA reported 75 = varies from 73-77 actual
GIA reported 80 = varies from 78-82 actual

Likely the same result if you have actuals of 77-78 which would show up as 75 or 80. However, the effect could be different if actuals were 73 and 82. Yet both would again show up as 75 and 80 on the lab report.

Make sense?

It does make sense. But aren't you safer choosing 80% in that scenario?

 

[AV_]

I simply point out that no one ever noticed the relationship between table size and LGF's.

I trust a cutter or two must have.

 

[Karl_K]

Karl I simply point out that no one ever noticed the relationship between table size and LGF's.

What ever your preference might be, then you simply can adjust LGF's up or down for a range of prospective table sizes.
The same can also be said for pavilion angles - for example for nice shallow pavilion and steeper crown angles the LGF's need to become longer or otherwise the table area becomes dark.

Agree about the pavilion angle but they can not be separated table size/pavilion angle and lgf% need to be taken together.
Take your lines on the chart, change the pavilion angle the chart changes, change the lgf% and the line changes, change the table% the line changes.

 

[chamois]

Interesting discussion. Thank you everyone

 

[sledge]

Agree about the pavilion angle but they can not be separated table size/pavilion angle and lgf% need to be taken together.
Take your lines on the chart, change the pavilion angle the chart changes, change the lgf% and the line changes, change the table% the line changes.

I feel this would be a good article write up, along with a nice reference chart of images to show the differences.

 

[Karl_K]

I went with a PA of 40.4 to make the arrows pop more.
The lgf% is @sledge favorite 75%.
Only difference is table sizes and changes that directly causes on the crown(upper angles etc. ).

 

[Karl_K]

 

[AV_]

This chart predates GIAs cut grading system of 2006 and so uses LGF length which is about 2% longer than GIA's LGF depth measuement.

What are the depths of these?

I have in mind a terrific pair of about 57% depth & 90% lgf ; larger tables that I might not recall properly, perhaps 67% -ish; mirror-like flat reflections & very, very bright - dream earrings. Who makes such things!

 

[sledge]

Thank you @Karl_K. I'm a visual person. The images do more than a million words, lol.

I had noticed this effect awhile back, and made a post about it in a VC thread. These aren't exactly perfect as your computer renderings, but they do show some real life examples.

Help picking a Canera H&A

Hello! I am currently in the process of buying an engagement ring for my girlfriend (hopefully, soon to be fiance) and have decided to get it from Victor Canera. I have been in contact with him already about the setting, a slightly modified Anne Marie where the modification is a slightly...

www.pricescope.com

Left stone = VC 1.558 G VS2
Right stone = VC 1.702 G VS2

Both have 77 LGF's. Biggest difference is in the tables. CA/PA combos are close but not exact.

1.558 = 56.7 table, 34.7/40.9
1.702 = 54.8 table, 34.9/40.8

Visually, the 1.702 gets me revved up. I like the fatter arrows and additional contrast.

That said, on the 1.702 I could see how an actual LGF value of 73-75 would be too much contrast and unattractive, whereas I might be okay with it on the 1.558 stone.

 

[Karl_K]

@sledge the differences in the real world would be far less.

Also welcome to the deep end you will never again look at diamonds like an "average" person would.