Is this considered deep/steep?
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FB.
Brilliant_Rock
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Crown is steep. Pavilion is normal.
But it will behave rather like a mild steep/deep; some leakage around the edge of the table is likely (a slightly dark ring when viewed straight-on).
It's possible that it might not be noticeable. Possibly rounding errors on the cert might mean that the angles are 40.7/35.25, which would be hardly noticeable.
But it will behave rather like a mild steep/deep; some leakage around the edge of the table is likely (a slightly dark ring when viewed straight-on).
It's possible that it might not be noticeable. Possibly rounding errors on the cert might mean that the angles are 40.7/35.25, which would be hardly noticeable.
Stone-cold11
Super_Ideal_Rock
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not necessary, depends on the averaging and round of angles. Do you have an Idealscope image of the stone?
FB.
Brilliant_Rock
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If it looks great to your eyes, then it might be one that has 40.7/35.25, rather than 40.8/35.5.
A steep/deep has a dark ring around the edge of the table (or completely dark underneath the table) when viewed from above.
Here's a mediocre picture of steep/deeps. The pair of stones on the left are true steep/deep. The one on the right is also steep/deep, but had some cutters tricks done to improve the performance - but the tricks got penalised by GIA as being non-standard cutting methods, so the stone graded GIA very good, despite easily qualifying as GIA EX on all it's proportions.
A steep/deep has a dark ring around the edge of the table (or completely dark underneath the table) when viewed from above.
Here's a mediocre picture of steep/deeps. The pair of stones on the left are true steep/deep. The one on the right is also steep/deep, but had some cutters tricks done to improve the performance - but the tricks got penalised by GIA as being non-standard cutting methods, so the stone graded GIA very good, despite easily qualifying as GIA EX on all it's proportions.
Stone-cold11
Super_Ideal_Rock
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What is the lower half number?
Should be on the profile diagram of the diamond, around 75-85%. If it is higher, in the 80-85% range, there probably would not have visible leakage, if lower you will have to look at it closely to check or get an Idealscope.
Should be on the profile diagram of the diamond, around 75-85%. If it is higher, in the 80-85% range, there probably would not have visible leakage, if lower you will have to look at it closely to check or get an Idealscope.
this is the exact proportion:
ROUND BRILLIANT
Measurements: 5.89 - 5.90 x 3.65 mm
Carat Weight: 0.78 carat
Color Grade: D
Clarity Grade: VS2
Cut Grade: Excellent
PROPORTIONS:
Depth: 61.9%
Table: 57%
Crown Angle: 35.5°
Crown Height: 15.5%
Pavilion Angle: 40.8°
Pavilion Depth: 43.0%
Star length: 50%
Lower Half: 80%
Girdle: Medium, Faceted (3.5%)
Culet: None
FINISH:
Polish: Excellent
Symmetry: Excellent
Fluorescence: Faint
CLARITY CHARACTERISTICS:
Crystal, Needle
ROUND BRILLIANT
Measurements: 5.89 - 5.90 x 3.65 mm
Carat Weight: 0.78 carat
Color Grade: D
Clarity Grade: VS2
Cut Grade: Excellent
PROPORTIONS:
Depth: 61.9%
Table: 57%
Crown Angle: 35.5°
Crown Height: 15.5%
Pavilion Angle: 40.8°
Pavilion Depth: 43.0%
Star length: 50%
Lower Half: 80%
Girdle: Medium, Faceted (3.5%)
Culet: None
FINISH:
Polish: Excellent
Symmetry: Excellent
Fluorescence: Faint
CLARITY CHARACTERISTICS:
Crystal, Needle
Stone-cold11
Super_Ideal_Rock
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With that lower half, it looks promising to me but again that is just a guess from the average and rounded values of the GIA report.
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Again images are needed to properly judge this diamond. Even longer lower girdle facets won't save it if the angles are not tight and swinging out all over the place, sorry but its only guessing as to whether this diamond will show leakage or not.
i think the people on this site have a strong bias towards high quality cuts. and why not, it is by far the most important determinant of performance? having said that, at the end of the day, a cut is still just one factor. another major factor - cost. not everyone on this site may be able to afford an AGS000. and to be honest, not everyone may want one. even HCA says "worth buying if the price is right." i mean, everyone would want an H&A AGS000 stone if it was the same price as an average stone, but its not - it''s a lot more.
if you cut the CA by 0.5%, it would score a 1.4 on HCA and then also be within the rough parameters of an AGS0/ideal. but am i really going to see that 0.5% CA difference in a 0.78ct stone? maybe i''ll see a bit of leakage on an ASET/IS blown up 50x, but what about in real life?
i''m just a consumer, but my guess is that if you took your stone and put it next to another one that was identical in every respect except for a 35% CA, that you probably wouldn''t be able to tell a meaningful difference in a 0.78ct stone. my advice would be to see the stone, try to compare it to an AGS ideal cut if available and see if you can see a difference. if you can''t, and the price is right, then go for it.
FB.
Brilliant_Rock
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The GIA cut grading system was largely determined by getting a large number of people to view a large number of stones.
However, it can be argued that the stones were not mounted and were in a different lighting environment to the average household or office.
But the fact remains that -for whatever reason- some people preferred steep/deep.
I suspect that in a steep/deep, the paler arrows (which seem to be reflective and contrasted against the slight darkness on the table) may have been what some observers found pleasing to the eye.
Certainly, my OH prefers stones that have the less-dark arrows - often found in deeper pavilion stones.
A stone of 40.4/35.0 would have quite prominent and contrasting black arrows.
A stone of 40.7/34 would have medium-intensity black arrows.
A stone with 41.0/33 has arrows that are only slightly contrasted.
It is interesting to note that GIA's excellent grade (determined by real observations) stops at 40.6 pavilion - suggesting a slight dislike of over-contrasted arrows and the steep/deep allows for arrows that are not too prominent.
Personally, a small amount of steep/deep - say up to about 41.0/35.0 or 40.8/35.5 would be acceptable to me, if it meant that I could achieve a certain carat/colour/clarity/cost milestone.
However, it can be argued that the stones were not mounted and were in a different lighting environment to the average household or office.
But the fact remains that -for whatever reason- some people preferred steep/deep.
I suspect that in a steep/deep, the paler arrows (which seem to be reflective and contrasted against the slight darkness on the table) may have been what some observers found pleasing to the eye.
Certainly, my OH prefers stones that have the less-dark arrows - often found in deeper pavilion stones.
A stone of 40.4/35.0 would have quite prominent and contrasting black arrows.
A stone of 40.7/34 would have medium-intensity black arrows.
A stone with 41.0/33 has arrows that are only slightly contrasted.
It is interesting to note that GIA's excellent grade (determined by real observations) stops at 40.6 pavilion - suggesting a slight dislike of over-contrasted arrows and the steep/deep allows for arrows that are not too prominent.
Personally, a small amount of steep/deep - say up to about 41.0/35.0 or 40.8/35.5 would be acceptable to me, if it meant that I could achieve a certain carat/colour/clarity/cost milestone.
Thanks Rockabee, I guess so, everyone wants their diamond to be at their absolute best, but how many can afford the absolute best? hehe I wont be able to afford that, I am just a plain jane looking for a decent looking good cut diamond 
Anyway, thanks all for the advices, the stone does look beautiful to me, but it seems to reflect more violet colours than other colours, which is why I am asking if this diamond is good, I did compare with my AGS000 diamond and they look pretty much the same, except that my AGS000 diamond is only 0.2ct, so may not e a good comparison I supposed... In fact, this one looks even more beautiful than my AGS000 0.2ct! I guess its due to size difference...
I took a look at the table top, dont see any dark ring on the table...
Anyway, thanks all for the advices, the stone does look beautiful to me, but it seems to reflect more violet colours than other colours, which is why I am asking if this diamond is good, I did compare with my AGS000 diamond and they look pretty much the same, except that my AGS000 diamond is only 0.2ct, so may not e a good comparison I supposed... In fact, this one looks even more beautiful than my AGS000 0.2ct! I guess its due to size difference...
I took a look at the table top, dont see any dark ring on the table...
FB.
Brilliant_Rock
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Right, I've cannibalised some images to compare.
You can see that the 35.0/41.0 on the left looks fine. That would also probably apply to a 34.5/41.2 or 35.5/40.8, but I'm not making a guarantee.
The 35.0/41.2 on the right shows the beginnings of the steep/deep characteristic dark ring around the edge of the table. The further the proportions move away from 34.5/40.8, the larger and darker the ring becomes.
You can see that the 35.0/41.0 on the left looks fine. That would also probably apply to a 34.5/41.2 or 35.5/40.8, but I'm not making a guarantee.
The 35.0/41.2 on the right shows the beginnings of the steep/deep characteristic dark ring around the edge of the table. The further the proportions move away from 34.5/40.8, the larger and darker the ring becomes.
Thanks for the illustrations FB... I think I am beyond hope haha, I look at both the AGS000 table top and the GIA triple ex stone, both looks like having a dark ring in the center.. but they seem to be form by the arrows, rather than outside of the arrow, not sure if you know what I meant..
Stone-cold11
Super_Ideal_Rock
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Narrower facets are the pavilion main facets, they will go black when you look at it within 14inch from the stone, at least the well cut ones do.
If the ring of darkness is not at the edge of the table, but in the center then that is just normal table reflection. Ring of darkness is when you can look through the pavilion. Try using a red/blue color blackground beneath the pavilion to differentiate light leakage from the shadow due to you.
If the ring of darkness is not at the edge of the table, but in the center then that is just normal table reflection. Ring of darkness is when you can look through the pavilion. Try using a red/blue color blackground beneath the pavilion to differentiate light leakage from the shadow due to you.
outatouch0
Shiny_Rock
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Not the best way to evaluate a stone IMHO. All stones look bright and sparkly in a jewelry store. In fact, all I can see inside the stores is GLARE!!! After awhile inside a B&M my eyes get such fatigue that I really can't see well at all.
I think next time I am going to bring in sunglasses just to see what happens (other than tripping out the SA's).
As for affording the best cut stone... Many here put cut quality as top priority and others do not. What are your priorities? It's about getting the best stone FOR YOU. I bet if you post your priorities and budget the members here will find several great choices for you to consider.
FB.
Brilliant_Rock
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Shallower pavilions tend have dark arrows against a light background, which can make the stone appear dark in the middle.
Steeper pavilions have light arrows agasint a dark background, which can make the stone apear dark in the middle.
Something in between is ideal - 34.5/40.8, 35.0/40.6, 34.0/41.0 is a good balance. You can push to 35.0/41.0 and still only barely notice the effect of steep/deep. But go to 35.0/41.2 or 35.5/41.0 and it will be obvious.
Slightly steep/deep seem to perform OK. I have one myself.
Severe steep/deep have impaired sparkle from the middle of the stone.
Steeper pavilions have light arrows agasint a dark background, which can make the stone apear dark in the middle.
Something in between is ideal - 34.5/40.8, 35.0/40.6, 34.0/41.0 is a good balance. You can push to 35.0/41.0 and still only barely notice the effect of steep/deep. But go to 35.0/41.2 or 35.5/41.0 and it will be obvious.
Slightly steep/deep seem to perform OK. I have one myself.
Severe steep/deep have impaired sparkle from the middle of the stone.
what about steep/shallow? i saw a 37/40.0 stone with 57 table that had fire coming out of the stars/bezel like crazy. but it had an absolutely dead center under the table. was i just seeing things or does the math work out such that those dimensions would have a dark center as well?
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Around 300 people, most in the trade, made 70,000 observations. "For whatever reason" may be attributable to the large obstruction metric (larger than AGSL's avg modeling by about 10 degrees). It explains the GIA metric's center, which favors steep/deep to shallow.
In real life viewing the appearance of the pavilion mains depends on the lighting conditions as well as the specific diamond. And diamonds are dynamic. Those "arrows" seen in magnified static images are tiny and will be flashing on-off, broken up by virtual facet-patterns in real life. Even when held still, lighting and viewer position influence how even the most symmetrical patterns appear. I'd mention also that the average level of cut quality doesn't produce crisp even "arrows" as we frequently see them here. Go into a mall store with a H&A viewer or ideal-scope and you'll find that such crisp patterning is a rare animal.
With that said, here is a look at a number of actual diamonds, all GIA EX.
1,3,5,7,9 are steeper than my normal recommendations but I'm an admitted cut purist: My goal is cutting for strongest visual appeal through the broadest range of normal lighting conditions. As such the GIA EX grade may be too wide for my personal taste - but I feel it's positive for consumers and its introduction in 2006 was a major boon for us all.
Now look at the images taken on white and black backgrounds, below. You can see how 2, 6, 8 change in appearance the least when the background is changed. Under-table leakage does crop up in some of the others. Whether such leakage is negative enough to concern you is a personal decision, but it's a factor that some experts avoid in diamond selection.
Article here.
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Then obstruction can be an issue, probably what you noticed by the sound of it. Obstruction can be seen in shallow shallow stones and shallow pavilioned diamonds, normally this is a darkening of the stone due to the viewer's head or body shadow blocking the light when a diamond is inspected closely. Such stones can look bright and sparkly when viewed at a distance.
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As a point of order (and for my personal OCD), the term "steep/deep" has different interpretations.
On this forum it begins with circa PA>41.0 combined with CA>35.0. I'm not going to argue the collective, especially since this is a threshold I agree is worthy of scrutiny, but please remember that everything needs to be taken as a whole. A little "give" here paired with a little "take" there can be fine.
Also, if you were to confront the average gemologist/jeweler about his 41.2/36.0 "steep/deep" you might get a loco-look. The old-school trade doesn't think "steep/deep" until the diamond is a virtual nail-head: Even now GIA defines 41.8 PA as "slightly steep" and 43.0 degrees as "steep." CA is "slightly steep" at 36.5 and "steep" at 40.0 degrees.
I think the Pricescope collective does a great job of protecting consumers, but regulars should know we use the term "steep/deep" here differently than people may encounter it IRL. There is nothing wrong with that. In fact there is much tradesmen and women can learn from discussion here about the most modern studies of cut - but do be aware of this difference.
On this forum it begins with circa PA>41.0 combined with CA>35.0. I'm not going to argue the collective, especially since this is a threshold I agree is worthy of scrutiny, but please remember that everything needs to be taken as a whole. A little "give" here paired with a little "take" there can be fine.
Also, if you were to confront the average gemologist/jeweler about his 41.2/36.0 "steep/deep" you might get a loco-look. The old-school trade doesn't think "steep/deep" until the diamond is a virtual nail-head: Even now GIA defines 41.8 PA as "slightly steep" and 43.0 degrees as "steep." CA is "slightly steep" at 36.5 and "steep" at 40.0 degrees.
I think the Pricescope collective does a great job of protecting consumers, but regulars should know we use the term "steep/deep" here differently than people may encounter it IRL. There is nothing wrong with that. In fact there is much tradesmen and women can learn from discussion here about the most modern studies of cut - but do be aware of this difference.
FB.
Brilliant_Rock
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35.0/41.0 is the borderline of where you can see steep/deep.
35.5/40.8 and 34.5/41.0 is probably similar, since if crown angle changes by 0.5%, pavilion angle needs to change by 0.1-0.2% in the opposite direction to balance out.
For completeness of what I mentioned earlier about the GIA excellent cut grade not allowing many stones with darker arrows; in stones with <40.5' pavilions.
Here's a pic of a 34.6/40.8 ideal on the left and a 35.0/40.2 (shallow pavilion) on the right. Notice the darker arrows under the table of the second stone. I believe that many here refer to it as "obstruction" - a reflection of your silhouette.
35.5/40.8 and 34.5/41.0 is probably similar, since if crown angle changes by 0.5%, pavilion angle needs to change by 0.1-0.2% in the opposite direction to balance out.
For completeness of what I mentioned earlier about the GIA excellent cut grade not allowing many stones with darker arrows; in stones with <40.5' pavilions.
Here's a pic of a 34.6/40.8 ideal on the left and a 35.0/40.2 (shallow pavilion) on the right. Notice the darker arrows under the table of the second stone. I believe that many here refer to it as "obstruction" - a reflection of your silhouette.
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