Diamond Symmetry
Posted by: | CommentsBottom Line Recommendation:
- Symmetry: “Good” or better is fine.
- Never, ever, ever pay more for “Triple Excellent” Diamonds!
What is Diamond Symmetry?
Diamond Symmetry refers to how well aligned the facets of a diamond are. i.e., do the edges of the facets on the top and bottom of the diamond line up along the girdle? Are the facets aligned symmetrically around the diamond?
Is Symmetry any more important than Polish?
The simple answer to that question is: not really. Take a look at the diagram on the right. Each of the problems mentioned there (off-center culet, off-center table, misshapen facets, out-of-round circumference, crown and pavilion misalignment, and a wavy girdle) can definitely take away from the beauty of a diamond. That’s not the issue. The issue is that, I, the diamond expert with 6+ years of experience can hardly tell the difference between a diamond with “Good” symmetry and “Excellent” symmetry. You will only see noticeable defects in symmetry as found in the diagram to the right in diamonds with a “Fair” or “Poor” symmetry grade. So like Polish, do not spend any additional money to buy a diamond with a “Very Good” or “Excellent” symmetry grade.
If you have any questions, please post them in the comments below. I will usually respond within 24 hours.
I’m going to be purchasing a cushion-cut diamond from a reputable whole seller in the extremely near future. One of the stones I’ve been eyeing is beautiful, but I’m concerned about its depth. Here are the relevant statistics:
Size: 1.52 c
Color: F
Clarity: VS2
Table: 52.0%
Depth: 72.1%
Dimensions: 7.00 mm x 6.34 mm x 4.57 mm
Symmetry: Good
Polish: Very Good
Price: ~12k
I know the most important thing is the the visual appearance of the stone, but I’m a numbers guy and don’t really have a good eye for this kind of thing. I’ve read that the depth “should” be less than 70%, and because the most important feature for me is the overall cut and brilliance of the stone, I’m concerned about this. So I have a few questions:
*Is a depth of 72% going to adversely affect the radiance or brilliance of the diamond?
*What about “good” symmetry, versus “excellent” symmetry? How does “good” polish compare to “excellent” polish? What about variance in the thickness of the girdle? Do these things really matter once the stone is set? (In case it’s relevant, I’m purchasing a halo setting).
*I want a stone that is more square than rectangular. The above has a length/width ratio of around 1.06; the one below has a ratio of about 1.10. I was told by one of the merchants that a halo setting will help “hide” the elongation, so I have a bit more leeway here than I would with different settings. Is this true?
The other stone I’m considering is a cushion modified brilliant with some different specs:
Size: 1.52 C
Color: G
Clarity: VS2
Polish: Excellent
Symmetry: Excellent
Dimensions: 6.62 mm x 6.22 mm x 4.22 mm
Girdle: Medium to Very Thick
Price: ~13K
Note that this is 8% more expensive despite the downgrade in color. I don’t know if this is because it’s somehow more beautiful than the former, or if it’s just because it has XX in polish and symmetry, and that these are merely rarity measurements that don’t really affect the appearance of the diamond.
The stones are held by different merchants so I can’t compare them side-by-side. Any suggestions would be greatly appreciated. Thank you.
(Both stones are GIA and also boast no fluorescence or culet).
Hi Confused. Here goes:
1) 72% depth will adversely affect the brilliance. Light will get caught inside the stone.
2) Good symmetry isn’t a problem. you can’t tell the difference between good, vg, or ex symmetry or polish.
3) Variance in girdle thickness is completely normal
4) Yes, it’s true about the halo masking a slight rectangular shape.
5) The XX probably adds to the price. Additionally, the other stone is probably relatively cheap for it’s color and clarity because of the big depth.
The truth is, though, that 13K for a G VS2 is expensive. See these better value alternatives:
http://www.jamesallen.com/diamonds/F-VS2-Ideal-Cut-Cushion-Diamond-1398012.asp
http://www.jamesallen.com/diamonds/F-VS2-Ideal-Cut-Cushion-Diamond-1353115.asp
Those are just for direct comparisons sake, but if you’d ask me, I’d recommend this stone for the same money:
http://www.jamesallen.com/diamonds/G-SI2-Ideal-Cut-Cushion-Diamond-1311788.asp
Sorry may i ask u this also – both F/VS2, one is 1.02ct, with two clouds in the middle of the table, but triple EX; the other is 1.03 , clearner table (with only a feather on the side of the table), BUT VG Symmetry, which one you think is better?
Whichever is cheaper.
Hi! What’s the price difference like between a VG and EX Symmetry? Many thanks!!
there really isn’t any
In your opinion is a yellow diamond w/good polish & symmetry at 1.66ct, cushion cut, & a depth of 61.9% w/faint fluorescence & at a VS2 based on egl report. Do you believe that is a good diamond w/good to fair resale value or retain value enough to be an heirloom piece? thank you so much for your time
Hi Tanya. Thanks for writing in. See our article about EGL certification. EGL certified stones are pretty much not a good value by definition.