What does 60/60 ring mean?

[gretag]

Rockdiamond did you miss this question or decline to answer?

Can you explain and describe GIA Cut grade Excellent 60/60 stones or combinations that you would not choose?

 

[Rockdiamond]

Spread is important, but comparing two AGS Ideal 0 diamonds 60/60 versus Tolk spread difference is likely the range of 3 - 5% better for a 60/60. So is that significant enough to warrant ignoring everythingelse?

Here, you're making it into a 100-0 situation. Of course we would not "ignore everything else"
IN fact there are clear visual differences between the Tolk and 60/60- and some will prefer the attributes of the 60/60, even if we ignore the spread.

But once you factor in the difference in size- ESPECIALLY if the observer prefers the scintillation of the 60/60, it's a clear cut winner.

 

[Rockdiamond]

The premise that fire is a non-factor is small diamonds is false. And one of the reasons is something referred to as 'bloom'. The fire event is perceived as much larger than the virtual facet that produced it.
This image captures both points.

Good one Brian!!
Getting a diamond to reflect a bright light does not equate to fire, and you surely know that.

 

[Texas Leaguer]

Bryan given that you have a lot of experience with the WF ACA and the typical 34.5/40.8/57 type of diamonds. Have you compared same or similar carat weight AGS0000 60/60 versus to a WF ACA?

Yes, I have compared them. Both are beautiful. Our criteria for ACA aim at the bullseye of the AGS Ideal range. With high precision facet execution (optical symmetry), we feel this approach best optimizes all aspects of diamond beauty.

 

[Rockdiamond]

Irrelevant to the discussion of whether the 5% extra spread gives you significantly more fire potential. That is a 300% difference which will dwarf any more subtle differences from cut.

What you seem to ignore, or fail to realize is that buyers of a one carat are not being told ( here on PS) that a stone of one carat is never going to produce near the fire of an equivalently cut 3ct. The issue of facet size and fire is crucial.
Also- if fire is the main objective, round isn't the best choice anyway.

To your other question- since I buy in person- with stones in hand, I'm not using measurements as a primary tool.
In other words, if I reject a stone, I'm not going to take a lot of effort to try and figure out the numbers of that diamond.
Plus, I don't buy a lot of colorless RBCs anyway. But I do look at many and have extensive experience with rounds over the years.

 

[Texas Leaguer]

Good one Brian!!
Getting a diamond to reflect a bright light does not equate to fire, and you surely know that.

I do know that. The image illustrates very small diamonds generating large flares of dispersed spectral color ('fire'), clearly much larger than the size of the facets producing them.

 

[Rockdiamond]

Brian, the metal on the back part of the bracelet is creating more "fire" or bloom, whatever you want to call it than the diamonds on the front part of the bracelet.
This just confuses the issue to people who have never seen fire in a diamond, or have seen it and not known what they were seeing.

 

[Texas Leaguer]

Here's another image of the same bracelet. Maybe easier to see what's fire and what's reflection.

 

[Rockdiamond]

OK Bryan- let's use my avitar.
ON the top portion, at the girdle, around 12:30 is a reflection of light- let's call it a flash. This is NOT fire.
The facet directly to the right of the culet is flashing the closest thing to fire in that picture.
Octavia does have good ability to disperse fire, as a general rule. But of course, the larger the Octavia, the more likely a person will be able to observe the fire.

 

[Rockdiamond]

Fire-2

• Rockdiamond
• May 3, 2017

Can we agree the areas I've pointed to show "fire"

 

[Texas Leaguer]

OK Bryan- let's use my avitar.
ON the top portion, at the girdle, around 12:30 is a reflection of light- let's call it a flash. This is NOT fire.
The facet directly to the right of the culet is flashing the closest thing to fire in that picture.
Octavia does have good ability to disperse fire, as a general rule. But of course, the larger the Octavia, the more likely a person will be able to observe the fire.

The green light at the 12:30 facet in your octavia is indeed fire. When light return is perceived as a single hue, that is the definition of fire. It is produced by refraction and the bending of light causing the ray to exit the diamond back to the eye with the wavelengths fanned out. This provides an opportunity for a narrow portion of the fan to be clipped by the pupil (or camera lens) such that only the wavelengths corresponding to that individual color is observed. When all the wavelengths of a fan hit the pupil, it is perceived as white light. It is possible for a facet to reflect multiple rays and mixing can occur. In your 12:30 example, you can see both white light return and and green 'fire'.

 

[Rockdiamond]

The green light at the 12:30 facet in your
octavia is indeed fire. When light return is perceived as a single hue, that is the definition of fire. It is produced by refraction and the bending of light causing the ray to exit the diamond back to the eye with the wavelengths fanned out. This provides an opportunity for a narrow portion of the fan to be clipped by the pupil (or camera lens) such that only the wavelengths corresponding to that individual color is observed. When all the wavelengths of a fan hit the pupil, it is perceived as white light. It is possible for a facet to reflect multiple rays and mixing can occur. In your 12:30 example, you can see both white light return and and green 'fire'.

I do see your point about the small green flash. The bright white reflection is far larger though.
Therefore a person viewing that event would not perceive fire- because the flash of reflection would prevent that- and it's much brighter and larger than the small fire event. IN person, I will not observe fire at that spot. The facet adjacent to the girdle has the ability to produce perceivable fire.

 

[Texas Leaguer]

I do see your point about the small green flash. The bright white reflection is far larger though.
Therefore a person viewing that event would not perceive fire- because the flash of reflection would prevent that- and it's much brighter and larger than the small fire event. IN person, I will not observe fire at that spot. The facet adjacent to the girdle has the ability to produce perceivable fire.

Depends on a lot of factors. Light source, distance of the observer, and even the size of your pupil. The smaller the pupil, the more likely it is to clip a section of the fan and see a fire flare.
This is why a mathematical construct for evaluating fire is so powerful. It predicts how likely it is to see fire in a given diamond. AGSL system allows the construction of fire maps (like ASET maps) that can show which facets or sections of a given diamond are most likely to produce fire.

 

[Rockdiamond]

Bryan, somehow you continue to neglect actual facet size in your factors.....

 

[Texas Leaguer]

Bryan, somehow you continue to neglect actual facet size in your factors.....

Ok, how's this for a summary of my general view, factoring in size:
Because of it's high refractive index a polished diamond is capable of producing significant amounts of Fire, one of the most illusive but magical attributes of any polished gem. Irrespective of the size of the diamond you are considering, cutting that sacrifices too much of this special attribute will result in a corresponding loss to diamond's potential beauty.

 

[bmfang]

The more that I study diamonds as a hobby and watch videos like the ones produced by Rhino for his YouTube channel, I'm becoming more convinced that facet size plays a part in determining whether a viewer will be able to notice fire and scintillation. Though we are talking about items that for the most part are less than 1cm in diameter. Hence, for me, if you were to compare two round diamonds, one cut in a modern brilliant and another cut in say an OEC, the OEC would produce more fire to my eyes due to the size of the facets pavilion side.

But for modern round brilliants, doesn't the lower girdle facet percentage play a major part in determining the size of the main pavilion facets which then can return light to the viewer as either bright white flashes under diffused lighting or as fire under more direct lighting conditions? Please forgive me if that question sounds stupid to you old hats as I'm a consumer who is wanting to constantly upgrade my knowledge (if not solely out of curiosity but also to help others who post in RockyTalky).

 

[Rockdiamond]

Yea, we don't agree Bryan. ( big surprise
That's very ....flowery- but if fire is a buyer's primary concern, the statement does not address the issue properly.
Furthermore, you're making broad assumptions that a diamond which is not likely to produce a lot of fire events is automatically sacrificing beauty.
You speak of sacrifices, but again, the relationship to a diamonds size is not in your equation.
The size is important in two areas
1) of a buyer is fire oriented, the size makes a huge difference.
2) maybe the sacrifices you speak of gives up fire events in exchange for a 3-5% increase in diameter. And it's entirely possible that the 3-5% increase in size will come with improved light performance for a given buyer.

 

[Rockdiamond]

The more that I study diamonds as a hobby and watch videos like the ones produced by Rhino for his YouTube channel, I'm becoming more convinced that facet size plays a part in determining whether a viewer will be able to notice fire and scintillation. Though we are talking about items that for the most part are less than 1cm in diameter. Hence, for me, if you were to compare two round diamonds, one cut in a modern brilliant and another cut in say an OEC, the OEC would produce more fire to my eyes due to the size of the facets pavilion side.

But for modern round brilliants, doesn't the lower girdle facet percentage play a major part in determining the size of the main pavilion facets which then can return light to the viewer as either bright white flashes under diffused lighting or as fire under more direct lighting conditions? Please forgive me if that question sounds stupid to you old hats as I'm a consumer who is wanting to constantly upgrade my knowledge (if not solely out of curiosity but also to help others who post in RockyTalky).

Thank you for asking!!
Yes, it does LGF% plays a large role in both fire events- as well as scinitllation associated with a more traditional 60/60 that will tend to have longer LGF's

 

[bmfang]

I note that Paul of CBI has sort of provided some responses re: fire over in another thread:
https://www.pricescope.com/communit...-best-for-fire-and-brilliance-sparkle.228069/

 

[Texas Leaguer]

bmfang,
You are quite correct. A well cut OEC can produce tons of fire. But there is a price to be paid in other areas. An MRB is a different animal. Both have devoted admirers.
With regard to lower girdle length and the production of fire, it is a good question. It certainly changes the scintillation dynamic with the longer LGF resulting in narrower mains and slightly smaller virtual facets. But if you look at AGS fire maps of rounds you will see that the crown area is the most likely to produce fire. That suggests to me that size of the mains may not be a prime determinant of fire, but certainly could be an important factor. It is generally true that you want to have a good mix of VF sizes.

 

[Rockdiamond]

I note that Paul of CBI has sort of provided some responses re: fire over in another thread:
https://www.pricescope.com/communit...-best-for-fire-and-brilliance-sparkle.228069/

Perfect bmfang!!
As you can see looking at the thread, the OP directly asks about size in relation to fire. The answers before Paul's show a lack of awareness regarding size and fire. this is the disconnect I'm speaking of.
Paul directly addresses fire in this part:

2. Fire

- Please note that there is distinction between dispersion (rainbows exiting the diamond) and fire (color being observed).
- When considering dispersion, one might be correct that more brightness means less dispersion. In that theory, size of the diamond makes no difference.
- In Fire however, there is a huge difference. With equal cut-quality, a bigger diamond has bigger 'virtual facets', and as a result, broader rainbows of dispersion exiting the diamond. The likelihood of one observing fire with a broader dispersion-fan increases a lot.
- As a result, with the same exact cut-quality, a bigger diamond will show more Fire than a smaller diamond.
- The latter observation has been shared regularly by our retailers, as our consistent cut-quality allows such comparison to make sense.

 

[Rockdiamond]

bmfang,
You are quite correct. A well cut OEC can produce tons of fire. But there is a price to be paid in other areas. An MRB is a different animal. Both have devoted admirers.
With regard to lower girdle length and the production of fire, it is a good question. It certainly changes the scintillation dynamic with the longer LGF resulting in narrower mains and slightly smaller virtual facets. But if you look at AGS fire maps of rounds you will see that the crown area is the most likely to produce fire. That suggests to me that size of the mains may not be a prime determinant of fire, but certainly could be an important factor. It is generally true that you want to have a good mix of VF sizes.

Please specify the price you are speaking of Bryan

 

[Texas Leaguer]

specifically overall brightness and scintillation. And most likely spread.

 

[Texas Leaguer]

An important aspect of VF size is faceting precision. Virtual facets are driven by primary and secondary ray bounces. When precision is not high virtual facets get scrambled and the VF facet size mix that was prescribed by the facet design get degraded as a result of 3D misalignments. Optical symmetry is very important to optimal light performance.

 

[Rockdiamond]

On spread, we agree, on average, round diamonds will have greater spread as compared to an OMB of the same carat weight.
With regards to Brightness and Scintillation- Perception plays such a crucial role in these aspects- the tools currently available can't come close to giving a consistent measurement which is useful to consumers in comparing different shapes.
Put another way- the LxW of a diamond is a hard number, which can be used to compare two diamonds.
There's simply no way to compare brilliance, brightness, or scintillation in the same objective manner.
Different observers will have different perceptions of these visual aspects.
What you might consider "paying a price" in brightness and scintillation might be "earning a dividend" to some observers.
I will say this- I am very glad to discuss these issues Bryan- you're extremely knowledgeable in a way I am not. I respect your studies- mine have been in a different sphere.
We're both very dedicated to consumer education, we just have different perspectives.
Peace my man

 

[bmfang]

Reading the (passionate) views of the two of you has certainly been educational. No chance that I could have this type of conversation with the jewellers that I know here in Australia (who essentially know the retail business well but who are not that knowledgeable about the products they are actually selling).

Totally get your point Bryan about the virtual facets needing to have optimal optical symmetry. I have noticed a distinct difference in brilliance and fire/scintillation in the BGD stone we purchased late last year compared with a regular GIA XXX my wife has had for a few years (which was great... until I started educating myself here on PS).

Excluding the 25 point difference in carat size (one is 96 points, the other a dead 70 pointer), the precision cutting of the facets in the BGD stone does bounce back a helluva lot more light compared with the non-ideal cut stone. I take both stones outside in daylight and it's very clear which is the better performing stone. I loupe both stones and I can see where the optical symmetry isn't there in the run of the mill GIA XXX.

 

[Texas Leaguer]

On spread, we agree, on average, round diamonds will have greater spread as compared to an OMB of the same carat weight.
With regards to Brightness and Scintillation- Perception plays such a crucial role in these aspects- the tools currently available can't come close to giving a consistent measurement which is useful to consumers in comparing different shapes.
Put another way- the LxW of a diamond is a hard number, which can be used to compare two diamonds.
There's simply no way to compare brilliance, brightness, or scintillation in the same objective manner.
Different observers will have different perceptions of these visual aspects.
What you might consider "paying a price" in brightness and scintillation might be "earning a dividend" to some observers.
I will say this- I am very glad to discuss these issues Bryan- you're extremely knowledgeable in a way I am not. I respect your studies- mine have been in a different sphere.
We're both very dedicated to consumer education, we just have different perspectives.
Peace my man

Brightness, leakage, dispersion, and contrast can be accurately assessed. Scintillation per se is not so easily graded and continues to be in the realm of 'taste'. Clearly, different people like different things and that's all to the good. The bottom line is seeing the diamond and knowing that it rocks your world.
Understanding some of the concepts and using the tools that are available today can significantly help consumers find the diamond that is right for them.

Always stimulating discussing these things with you David.

P.s. Saw a great concert this weekend. Jesse Cook flamenco style guitar virtuoso with his small band of superb musicians. If you ever get a chance, you will not be dissappointed.

 

[Rockdiamond]

Thanks for the recommendation Bryan!
This guy?
WOW!

 

[Sagefemme]

There is something wonderful about this thread--two diamond experts going head to head, passionate about their views and having so much expertise, and being a bit at each other's throats sometimes, and then.............flamenco music for the finale. Thanks for all the great arguments. I learn a lot from y'all.

 

[Texas Leaguer]

Music is the universal language and certainly has a way of bringing people together. I discovered some time back that David is a musician. Although I'm not a player, I love music.

To me it's kind of like fishing - no matter what, if you're a fisherman you can't be all that bad!