60/60 round brilliant?

[Rockdiamond]

Interesting John- my experience is that well cut stones with smaller virtual facets do very well in low lighting, even in stones under 1.00ct.....

The conventional wisdom is that larger VFs help visibility in low-light conditions. This is the reason antique rounds, which were fashioned under the gas lamp, were cut with extremely wide pavilion mains; their lower halves were around 40% until Morse lengthened them to 60% around the turn of the 20th century. You probably know that, almost a century later, Eightstar created a formula within the modern RB combining short lower halves by today's standards (73-77%), painted upper-halves - basically serving to "couple" every two facets into one all the way around the crown - and top cut-precision to maximize the size of the resultant VFs. While their painted-crown treatment now takes a hit in modern cut metrics Eightstar's reputation for bold, visible colored flashes in low-light conditions remains unrivaled in a modern RB. It was all a result of strategic upper and lower-half choices, amplified by cut-precision, to increase VF size ~ before we were even talking about VFs.

In favor of your experience though, top cut-precision does give crisper-contrast and harder "edges" to VFs, so it increases visibility regardless of size. In low light your pupils may dilate which can increase the chance you will perceive color...but that's a tricky topic which depends on number and intensity of light sources as well as how they collectively sub-tend light. That detail is related to why fine diamonds can go "dark" at their cores in sunlight; because the sun sub-tends light at only 1/2 of a degree in a 180-degree hemisphere.
John, what I read in your reply is that results are mixed- so we can't really give an "edge" to larger or smaller VF's over a broad range of lighting environments- yes?

John, from my perspective, the italicized portion of your post only continues the "anti 60-60" sentiment which is wrongly put forth here. Where are all these sub par 60/60's you speak of? Truth is, I have a hard time finding stones with these proportions today as cutters try to imitate "ideal" cuts. If I look at 10 triple EX GIA graded stones, it's likely no more than 1 or two have 60% tables. Then we have the fact that less CA/PA angles qualify for EX or 0 cut grades in stones cut to 60/60.

GIA's new cut-grading requirements have absolutely depleted the abundance of 60/60 makes on RapNet and similar B2B sites... But you'll still find them abundantly in popular chain stores, department store jewelry counters and other discount outlets selling finished jewelry. And those places make up a huge segment of the USA diamond market. Those stones are not listed in our trading networks; they go from upstream cutting houses to international wholesalers to parent buying organizations (think Zalecorp, Finlay, Buffet, Sterling...) are assembled into jewelry and directly distributed. They do not pass through GIA and are often held to no cut-quality requirements to speak-of. Such makes can also be found on the streets and shops of diamond districts in other countries, although less and less in the Asia-Pacific theater these days.
John, I know , after all these years, you'd prefer I be honest here: Your statement above sounds like Dancing Fire- who bought the ugliest diamond in the world, and it somehow turned into a 60/60 in many discussions here over the years.
Your comment about how abundant 60/60 stones are is, IMO, totally misplaced. Unless you've been going around to chain and department stones with a microscope, and measuring tools, how can anyone say what proportion sets are necessarily abundant specifically.
My experience includes filling orders for stores like Zales- but that was years ago. Today , however, I get to look at thousands of stones, from a wide array of cutters. The off made goods I see range from flat pancake type stones- to off kilter twisted stones- to heavy makes with dark centers. It is today, as it's always been in my experience- off make goods are inconsistent. There is not a higher percentage of 60/60's among off make goods compared to badly cut stones with smaller tables
We agree badly cut stones are prevalent in some large chain and department stores- however calling these stones 60/60 arbitrarily promotes the misconception ( here) that 60/60 is something of a problem.
Instead, how about we take our microscope and measuring tools to the most prestigious stores on Fifth Avenue- where we very likley would find some extraordinary 60/60's

I ran a check on RapNet - where there are admittedly more non-60/60s - so you can see where my "sub-par" comment comes from.

60/60s: A search today produces 35,306 diamonds (GIA/AGSL only) tables 59-61 with Ideal-Ex cut grades. The same search produces 31,054 diamonds with VG-P cut grades...pretty similar numbers. For table 60 exclusively there are 11,010 Ideal-Ex and 10,237 VG-P. Those numbers are even more similar.

Near-Tolk: A search produces 114,839 diamonds (GIA/AGSL only) in tables 53-58 with Ideal-Ex cut grades. The same search produces 70,355 with VG-P cut grades. Bear in mind that this search spans 2X as many table sizes as 59-61% and 6X as many as table-60-only, but returns far more (supposed) "top" cuts than "non-top."

So RapNet - our most revered trade-to-trade network - declares the number of "Non-EX" 60/60 options to be nearly as abundant as "Ideal-EX" 60/60 options. Meanwhile there is a much larger number of "Ideal-EX" Near-Tolk options than "Non-EX."

Now consider that many educated folks believe the GIA "EX" system is already pretty accommodating. This means that many of the potential "EX" candidates returned on RapNet (across all makes) may be rejected by cut-focused folks.
As already mentioned- just how many EX cut grade stones are 60/60 is not relevant to any individual looking for a diamond- if they want a 60/60 stone. AGSL graded 0 cut grade princess cuts are also rare- but for someone who wants one, that's not the issue

Add to this the fact that the Pricescope enthusiasts are specialized in being numbers-demanding and cut-particular. Remember that the majority of Near-Tolk options that appear here have been culled and posted by vendors who understand this marketplace. The random 60/60s do not enjoy such culling beforehand - and that does not work in their favor. Without the benefit of pre-selection by vendors targeting this cut-focused market it's no surprise that 60/60s get dismissed with greater frequency.
Another issue that I find here on PS John- people claiming they're part of a group. "Oh, here at PS, we like... There is no group other than some very vocal members who repeat the same mantra over and over ( think "cheat sheet")
Instead we have a lovely diverse group of folks- many of whom are enthusiasts with differing views on these subjects

So, from the perspective of one who would prefer a more even handed approach to assisting consumers, I still see a problem. Although I do disagree with a few statements made in this thread, I know we share the same goal John.

We always have.

You know, one thing that could change the perception, David, is if someone would start specializing in 60/60s with terrific ASET images and great cut-precision here; posting a suite of photos online just as the sellers of near-Tolkowsky makes do. The consumer-knowledge on Pricescope has been gained through years of experiences which include trial, error, success and failure. I continue to see plenty of near-Tolk diamonds spewed into the "real-world" that would get hammered here, even though PS standards have softened over the years.

If someone (you?) would bring an inventory of scientifically-supported 60/60s to this market, demonstrate their appeal and price them aggressively perhaps avenues would open up which would make you happy in the aforementioned 60/60 tummy.

Interesting, and likely influencing how many EX cut grade 60/60's I see, but I know you'll agree, percentages of stones that are "this" or "that" are in no way relevant to any given discussion about a given stone.

Absolutely. And shame on us for so gruesomely hijacking a thread that has nothing to do with this particular discussion... "Plus ça change..."

Part of our difference of opinion lies in the fact that I consistently find that my eyes tell me things that contradict the"scientifically supported" tests used here frequently.
Yes, I wish there was less emphasis by cutters on trying to copy Lazaare Kaplan "ideal" make, versus a nice spreadier stone like a 60/60- but there's really business model that would support that- however discussions like these are a move in the right direction- Now we need to get rid of that misleading "60/60 tutorial".....

 

[Dancing Fire]

RD...my 60/60 was a flat top stone... i wouldn't mind a 60/60 with crown height...

 

[goodgal]

What is a flat top stone?

 

[Rockdiamond]

Hi DF!!

I think my point in our discussions has always been.....I'm sure it was very bady cut DF- of that, I have no doubt.
my question is that whether or not the stone you had- the pancake flat top- was indeed 60% table, 60% depth we won;t get to find out- unless you still have the diamond.
Since there was no GIA report, or Sarin we can't know exactly what the proportions of the badly cut stone were-

goodgal- when we look at a diamond in profile, some of them have flat tops- others have a higher crown. If we're looking at well cut diamonds it's balanced

 

[Dancing Fire]

Hi DF!!

I think my point in our discussions has always been.....I'm sure it was very bady cut DF- of that, I have no doubt.
my question is that whether or not the stone you had- the pancake flat top- was indeed 60% table, 60% depth we won;t get to find out- unless you still have the diamond.
Since there was no GIA report, or Sarin we can't know exactly what the proportions of the badly cut stone were-

goodgal- when we look at a diamond in profile, some of them have flat tops- others have a higher crown. If we're looking at well cut diamonds it's balanced

didn't need a GIA report on this stone. i can see it with my naked eyes that this stone had no crown height. when i purchase the stone the jeweler said it was a 60/60 stone.

 

[Rockdiamond]

DF: if someone came here and mentioned that a jeweler had told them a given stone was "a perfect cut"- yet there was no GIA or AGS report we'd advise them not to trust a seller based only on his word
This is exactly the same thing- sure, you identified the stone as flat. Sure it may have been badly cut.
But you have no way of knowing what the table and depth was on the diamond.
As I mentioned, badly cut goods are inconsistent- but if a stone was 60 depth and table it most likely was NOT a 60 table, 60 depth.
But since there is no conclusive evidence all it looks like is an attemp to make a given type of cut look bad arbitrarily
Which is part of my point and has been all along

 

[Unknown]

Very interesting!
I find two, any thoughts on them?
Diamond 1


Measurements: 6.49 - 6.51 x 3.90 mm
Carat Weight: 1.01 carat
Color Grade: G
Clarity Grade: SI1
Cut Grade: Excellent
PROPORTIONS:

Depth: 60.0%
Table: 60%
Crown Angle: 33.0°
Crown Height: 13.0%
Pavilion Angle: 41.0°
Pavilion Depth: 43.0%
Star length: 50%
Lower Half: 80%
Girdle: Medium to Slightly Thick, Faceted
Culet: None
FINISH:

Polish: Excellent
Symmetry: Very Good
Fluorescence: Medium Blue



Diamond 2

Measurements: 6.52 - 6.57 x 3.88 mm
Carat Weight: 1.01 carat
Color Grade: G
Clarity Grade: SI1
Cut Grade: Excellent
PROPORTIONS:

Depth: 59.2%
Table: 60%
Crown Angle: 32.5°
Crown Height: 12.5%
Pavilion Angle: 41.0°
Pavilion Depth: 43.5%
Star length: 50%
Lower Half: 80%
Girdle: Medium, Faceted
Culet: None
FINISH:

Polish: Excellent
Symmetry: Excellent
Fluorescence: Strong Blue