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Smaller circle in the middle?

Decision_Decisions

Shiny_Rock
Joined
Apr 29, 2016
Messages
297
Are there proportions specifically that give a diamond a smaller circle in the very center? I don't know if there is a name for that area of the stone. I am comparing two diamonds and I like the look of the one on the right because the arrows are thicker and appear to me to come closer together in the center of the stone. The drawbacks of the stone on the right are that it is warmer in color and has an inclusion on the table that I'm not sure about. In general I know that both of these stones will be amazing and perform beautifully. But by the looks of them, would you say that one of them would perform better than the other?

I can share the proportions if it matters, but for my future searches I'm just interested to hear if there are numbers or combinations specifically that produce those thicker arrows with a smaller center area. Is it the lower girdle %? There is a 1% difference between the two. Thanks!

Comparison.jpg Comparison2.jpg
 
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diamondseeker2006

Super_Ideal_Rock
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57,716
You are definitely overanalyzing if you are looking at the circles in the center. =)2 But it's okay to have a preference of fatter arrows over skinny arrows, or vice versa. The arrow width is the lower girdle facet %. In superideal cuts, you'll generally see 76-78%. Unless you are looking at huge diamonds, you can't really tell much difference in those percentages. A 1% lgf difference is not enough to let that be a deciding factor. I'd go for higher color or higher clarity or greater size...whatever factors are most important to you. Both stones will be beautiful, but I'd say color will be the most apparent difference between 2 similarly sized superideal cut diamonds. Of these two stones, I can tell you without knowing any other information that I'd choose the one on the left that has better color and clarity.
 

sledge

Ideal_Rock
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Apr 23, 2018
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5,197
I easily see stuff like this too.

The stone on the right has a smaller table. It may or may not have numerically smaller lower girdle facets (LGF's) than the stone on the left. Generally speaking smaller LGF's = fatter arrows, whereas larger LGF's = skinny arrows.

1621316819307.png

Also on the hearts image, the V shape will be more skinny on a smaller LGF, and as the LGF increases, that gap will get thicker.

1621316803305.png

However, it gets tricky. It's possible for two stones to both have 77 LGF's, but one have a 57 table and the other a 55 table. Although LGF's are the same, the arrows will look more fat on the stone with the smaller table.

I might add that smaller LGF's also favor indirect/low lighting and can throw slightly bolder flashes of rainbow light, whereas larger LGF's will perform better in brighter overhead lighting and throw a little more white light.

The imagery tells me both these stones are from WF. Super ideals normally vary from 76-79, so not much difference with 77-78 kind of being a sweet spot of balance.

I love it when you find a small 54/55 table with a 76 LGF. :love:

 
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Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
16,518
The table reflection is what you are looking at. The light that falls in that small circle leaves via the table. The light in between the table and the circle (the donut around it) leaves via the opposite side crown facet.
The main issue is the pavilion angle. At 40 degrees there is almost zero table reflection. At 45 degree the table reflection takes up the entire table and is dark because you are looking at yourself and no lights get returned - called a nail head. Until recently GIA and almost all the dumb education on websites call that darkness leakage. It is not.
Larger tables have larger table reflections.
Crown angle and girdle thickness variations also make slight adjustments to the above.
 

Decision_Decisions

Shiny_Rock
Joined
Apr 29, 2016
Messages
297
Thanks everyone, that's exactly the information that I'm looking for! I am surely over analyzing but it's really apparent to me as part of the overall look of the diamond (and also a huge purchase for me). There are always compromises of course even in the land of the "perfect" super ideals.
 

diamondseeker2006

Super_Ideal_Rock
Premium
Joined
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Messages
57,716
Thanks everyone, that's exactly the information that I'm looking for! I am surely over analyzing but it's really apparent to me as part of the overall look of the diamond (and also a huge purchase for me). There are always compromises of course even in the land of the "perfect" super ideals.

Still, the point is, a superideal vendor already has a very narrow range of specs. What size diamonds are you looking at? I have 1.6 ct ACA's and the little circle in the center from table reflection is basically pinpoint size! That's how small it is in real life viewing. My lgfs are 77, believe. As I said before, you'll find most ACAs with 76-78 lgfs, so if you have the idea you like the fattest ones best, then stick with 76 and 77 for lgfs.

Just out of curiosity, what is the table size of those two stones? And what size are they?
 

yssie

Super_Ideal_Rock
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Aug 14, 2009
Messages
22,535
There are always compromises of course even in the land of the "perfect" super ideals.
The table reflection unto itself is not (ever) considered a signifier of excellence or compromise. It's the product of relationship between table size and pavilion angle - these two measures, table size and pavilion angle, absolutely are segmented into ranges of "bad/good/better/best", but the table reflection that happens to be a side-effect of various combinations is just that, a side effect. It's never a goal. The stone on the left isn't a compromise compared to the stone on the right. The stone on the right isn't more perfect than the stone on the left.

You may have a personal preference for a smaller table reflection - this is perfectly fine and valid, and you'll need to adjust your personal parameters to specific ranges to yield that desirable-to-you side effect. But realize this is your personal preference, not an industry-wide or consumer-wide judgment.
 
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Decision_Decisions

Shiny_Rock
Joined
Apr 29, 2016
Messages
297
Still, the point is, a superideal vendor already has a very narrow range of specs. What size diamonds are you looking at? I have 1.6 ct ACA's and the little circle in the center from table reflection is basically pinpoint size! That's how small it is in real life viewing. My lgfs are 77, believe. As I said before, you'll find most ACAs with 76-78 lgfs, so if you have the idea you like the fattest ones best, then stick with 76 and 77 for lgfs.

Just out of curiosity, what is the table size of those two stones? And what size are they?

Just as everyone assumed, the one on the left has a larger table 56.4 paired with 78 lgfs while the one on the right has a smaller table at 55.3 paired with 77 lgfs. They are in the 1.75ish range.
 

Decision_Decisions

Shiny_Rock
Joined
Apr 29, 2016
Messages
297
The table reflection unto itself is not (ever) considered a signifier of excellence or compromise. It's the product of relationship between table size and pavilion angle - these two measures, table size and pavilion angle, absolutely are segmented into ranges of "bad/good/better/best", but the table reflection that happens to be a side-effect of various combinations is just that, a side effect. It's never a goal. The stone on the left isn't a compromise compared to the stone on the right. The stone on the right isn't more perfect than the stone on the left.

You may have a personal preference for a smaller table reflection - this is perfectly fine and valid, and you'll need to adjust your personal parameters to specific ranges to yield that desirable-to-you side effect. But realize this is your personal preference, not an industry-wide or consumer-wide judgment.

Thank you that's helpful! I'm glad to know that there will be no trade offs in performance between the stones and that it just comes down to balancing preferences with costs and availability.
 

sledge

Ideal_Rock
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Joined
Apr 23, 2018
Messages
5,197
Thank you that's helpful! I'm glad to know that there will be no trade offs in performance between the stones and that it just comes down to balancing preferences with costs and availability.

While table reflection is a by-product of other variables that doesn’t affect performance, the other variables themselves can affect performance.

In a super ideal those variances will be very minimal as they are all magnificent and designed & cut to be top performers. But it’s possible to find different “personalities” within super ideals based on table, CA, PA, LGF, etc

Those personalities may be easier to spot in magnified videos but will be harder to identify IRL with the naked eye.

In short, ACA’s are going to great whatever you choose but if you have a few your deciding amongst its these minor things that may tip your decision one way or the other.
 

Decision_Decisions

Shiny_Rock
Joined
Apr 29, 2016
Messages
297
While table reflection is a by-product of other variables that doesn’t affect performance, the other variables themselves can affect performance.

In a super ideal those variances will be very minimal as they are all magnificent and designed & cut to be top performers. But it’s possible to find different “personalities” within super ideals based on table, CA, PA, LGF, etc

Those personalities may be easier to spot in magnified videos but will be harder to identify IRL with the naked eye.

In short, ACA’s are going to great whatever you choose but if you have a few your deciding amongst its these minor things that may tip your decision one way or the other.

Thank you for this, this is helpful. I like the way you phrased that, as the different stones having different personalities. I think that the size of the table reflection may be somewhat like color for me, in that it won't be as noticable unless I'm holding it next to a stone with a smaller table reflection (or higher color).

But I also feel like now that I've seen it and understand the relationship it will likely be something I always notice. Like you, I'm also noticing that 55ish table and LGF's of 76 look extra pleasing to my eye, at least in the magnified images.
 
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