round brilliant diamond specs
- Thread starter bougainvillier
- Start date
I am not Ame but I am an online friend of Ame from a diamond forum.
I would be afraid that stone would have leakage because of the angles. The pavilion angle needs to be lower with that crown angle. Sticking to these measurements will be safest, and we always recommend an idealscope image, as well.
table: 54-58
depth: 60-62.3
crown angle: 34-35.0
pavilion angle: 40.6-41.0
HI DS! *waves*
Thank you for starting your own thread. Sorry for being tardy to the party! I would be happy to elaborate in here. The reason I said "no" on that stone is that the interplay on those specific angles is not ideal, nor is the table percentage. Specifically: the crown and the pavilion angles are too flat in ratio to each other, so light is not going to properly reflect back up out of the stone like it should, and you will likely get a "ring" of darkness in the stone where the light just goes right through it. If either angle was a bit steeper, it would reflect more light back through the top of the stone, and you would get significantly better results. A 58% table is outside the lines on a true ideal, but when used with the proper crown and pavilion angles and a depth around upper 61s-62%, can work out ok.
Something to note about stones with "larger" tables is that they reflect more white light than colored light, meaning you'll get more white flashes than rainbow sparkles. "Smaller" tables tend to produce more colored light than white light, meaning you get more rainbow sparkle than white return. To many untrained eyes, it's not noticeable, but to someone like me, that's more obvious.
I personally have a hard time "believing" the GIA cut grading system of "excellent" because it's a HUGE net of what falls under excellent (note: GIA does NOT use the term IDEAL, that is AGS), where AGS has significantly tighter ranges than that. You can sometimes see that a GIA Very Good graded stone is actually more beautiful and has better numbers than what they might call Excellent, which I just find so bizarre, and AGS might grade the VG and Ideal/0, and the Excellent a 1.
In general, to really nail it on the perfect proportions, a general cheat sheet to stick to:
Total depth between 59 – 61.8%
Table diameter between 53 – 57%
Crown angle between 34.3 – 34.9 degrees
Pavilion angle between 40.6 – 40.9 degrees
Girdle thickness between thin to medium, faceted (bruted isn't bad, but faceted would be better)
Culet size: none
When you're dealing with a table of 53-54, you want the depth to be in the 59-60 range, not the 61-62 range. I harp on the 55 because it's RIGHT in the middle of the range, and when the angles jive nothing beats the light return.
The angles mentioned in degrees are a range, obviously you're going to have interplay, so there's not a specific ratio there, ideally a 34.5 crown and a 40.7-40.8 pavilion, but that's not always going to happen. You have to see what the numbers on each stone are.
We'll gladly chime in if you have more stones you want input on.
Thank you for starting your own thread. Sorry for being tardy to the party! I would be happy to elaborate in here. The reason I said "no" on that stone is that the interplay on those specific angles is not ideal, nor is the table percentage. Specifically: the crown and the pavilion angles are too flat in ratio to each other, so light is not going to properly reflect back up out of the stone like it should, and you will likely get a "ring" of darkness in the stone where the light just goes right through it. If either angle was a bit steeper, it would reflect more light back through the top of the stone, and you would get significantly better results. A 58% table is outside the lines on a true ideal, but when used with the proper crown and pavilion angles and a depth around upper 61s-62%, can work out ok.
Something to note about stones with "larger" tables is that they reflect more white light than colored light, meaning you'll get more white flashes than rainbow sparkles. "Smaller" tables tend to produce more colored light than white light, meaning you get more rainbow sparkle than white return. To many untrained eyes, it's not noticeable, but to someone like me, that's more obvious.
I personally have a hard time "believing" the GIA cut grading system of "excellent" because it's a HUGE net of what falls under excellent (note: GIA does NOT use the term IDEAL, that is AGS), where AGS has significantly tighter ranges than that. You can sometimes see that a GIA Very Good graded stone is actually more beautiful and has better numbers than what they might call Excellent, which I just find so bizarre, and AGS might grade the VG and Ideal/0, and the Excellent a 1.
In general, to really nail it on the perfect proportions, a general cheat sheet to stick to:
Total depth between 59 – 61.8%
Table diameter between 53 – 57%
Crown angle between 34.3 – 34.9 degrees
Pavilion angle between 40.6 – 40.9 degrees
Girdle thickness between thin to medium, faceted (bruted isn't bad, but faceted would be better)
Culet size: none
When you're dealing with a table of 53-54, you want the depth to be in the 59-60 range, not the 61-62 range. I harp on the 55 because it's RIGHT in the middle of the range, and when the angles jive nothing beats the light return.
The angles mentioned in degrees are a range, obviously you're going to have interplay, so there's not a specific ratio there, ideally a 34.5 crown and a 40.7-40.8 pavilion, but that's not always going to happen. You have to see what the numbers on each stone are.
We'll gladly chime in if you have more stones you want input on.
Hey, Ame!!!
Ame has narrowed down the specs a little more than I did, and I will agree that 55-56 table and 34.5 and 40.8 are about THE most ideal numbers! I did have a hearts and arrows diamond with those exact measurements (depth was about 61). But I also had one with 58 table, 35 and 41 for the angles, (and I don't remember the depth but it wasn't more than 62), and it did get ideal for light performance as a GIA XXX. I couldn't tell any difference in light performance between the 56 and 58 tables, so that may be why I am a little more comfortable with the wider ideal cut range.
Ame and I both really love finely cut diamonds, and we try to give numbers that will result in a diamond likely to be a great choice. But again, the pictures and idealscope images will be the final test to see if there is any leakage that would be of concern.
Ame has narrowed down the specs a little more than I did, and I will agree that 55-56 table and 34.5 and 40.8 are about THE most ideal numbers! I did have a hearts and arrows diamond with those exact measurements (depth was about 61). But I also had one with 58 table, 35 and 41 for the angles, (and I don't remember the depth but it wasn't more than 62), and it did get ideal for light performance as a GIA XXX. I couldn't tell any difference in light performance between the 56 and 58 tables, so that may be why I am a little more comfortable with the wider ideal cut range.
Ame and I both really love finely cut diamonds, and we try to give numbers that will result in a diamond likely to be a great choice. But again, the pictures and idealscope images will be the final test to see if there is any leakage that would be of concern.
Thanks ame, I know this has been a while but I am interested to follow up on this again... (I am thinking about an upgrade, just maybe
) Specifically, I am looking at three round diamonds here and wondering if you can offer further help on comparison, so to put your analysis into practice.
Diamond 1.
table 57, depth 61.8, angles 34.5/41.2. I think this one is the closet according to your specs above (or the table/depth is too large so less fire more white light?), but it has inclusions right on the table, VS2, H color with no fluro
Diamond 2.
table 56, depth 59.8, angles 32/40.8, is this angle too bad? VVS1, I color with no fluro
Diamond 3.
table 56, depth 60.9, angles 34/40.8. also VS2, I color with no fluro. I want to guess this one is the best among three. Just guessing...
I know it might sound silly but I am really ignorant here - when you talk about the specs above, I felt it's hard for me to understand unless we are talking about specific diamonds. So there are three. If you'd choose one, which?
Also what should I look for Girdle? Culet? Are these less important if I got a really good cut, or it matters much?
What is the interplay between cut and inclusions? I am looking at 2 - 2.3 ct range. IS VS2 a deal breaker regardless of how good your cut is?
Lastly, I don't really mind lower color stone, I have yellow gold settings and like the warmth of an I or even J. Am I insane here? Should I stay with H?
Thanks much!!!!
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#3 is the best one of the three. If I was met with these three, and I was pleased with the clarity of the VS2, that would be the one out of this bunch I'd select. The table and depth are great together, and the crown and pavilion angles are nice together as well.
I would not consider your concern "insane" but I would not personally have an issue with an I without Fluorescence, but if you're concerned about warmth--and it sounds like you're not--then go up. But I see no reason to go up in color, esp if you want a gold setting. You'll really only detect the warmth from the side, face up it should be quite bright.
A 57% table (assuming it's 57.0) is well within the limits for ideal. That's where you start getting into whiter light return vs color light return--fire. The smaller end, 55, will get you more color light vs whiter light return. Some people can't tell, some can. But you will notice that you're going to find a LOT more on the 57 end than the 55 end because they're easier to get a quality cut grade and preserve carat weight from.
Regarding your VS2 question--that depends on the type of inclusion, really, but MOST VS2s should be eye clean, and the light return should not be impacted by 99% of all VS2 graded inclusions--assuming its a GIA or AGS anyway. Most of the grademakers I've seen in VS2s are a dark crystal in the table, or a feather of some kind which are in an annoying location, but they usually don't inhibit light return in most cases. What you need to inspect for is clouds, many of which won't be outright indicated on the stone's plot, and instead will be mentioned as "not shown" and those CAN inhibit light return in some extreme cases. But if they're impacting light return, they're not likely to be in the VS category.
Girdle-Thin to Medium, faceted if possible (bruted isn't bad)
Culet-None
Does this stone have a report? From which lab? Is there an IdealScope or ASET image to accompany it? If it's an online vendor, send me a link in a PM.
I would not consider your concern "insane" but I would not personally have an issue with an I without Fluorescence, but if you're concerned about warmth--and it sounds like you're not--then go up. But I see no reason to go up in color, esp if you want a gold setting. You'll really only detect the warmth from the side, face up it should be quite bright.
A 57% table (assuming it's 57.0) is well within the limits for ideal. That's where you start getting into whiter light return vs color light return--fire. The smaller end, 55, will get you more color light vs whiter light return. Some people can't tell, some can. But you will notice that you're going to find a LOT more on the 57 end than the 55 end because they're easier to get a quality cut grade and preserve carat weight from.
Regarding your VS2 question--that depends on the type of inclusion, really, but MOST VS2s should be eye clean, and the light return should not be impacted by 99% of all VS2 graded inclusions--assuming its a GIA or AGS anyway. Most of the grademakers I've seen in VS2s are a dark crystal in the table, or a feather of some kind which are in an annoying location, but they usually don't inhibit light return in most cases. What you need to inspect for is clouds, many of which won't be outright indicated on the stone's plot, and instead will be mentioned as "not shown" and those CAN inhibit light return in some extreme cases. But if they're impacting light return, they're not likely to be in the VS category.
Girdle-Thin to Medium, faceted if possible (bruted isn't bad)
Culet-None
Does this stone have a report? From which lab? Is there an IdealScope or ASET image to accompany it? If it's an online vendor, send me a link in a PM.