Symmetry can anyone really tell the difference?

[treasurehunter]

Say I placed 3 ideally proportioned stones of the exact same proportions on a tray next to each other, one being Hearts and arrows the other being excellent and the other being very good.

Without the use of ideal scope or a loupe or a hearts and arrow viewer would anyone be able to tell the difference?

 

[kaoms352]

Yes but that is not really symmetry, that would be the cut grade.

Look at goodoldgold.com they have lots of educational videos that compare.

 

[treasurehunter]

Thanks I found a video of two stones of ideal proportions being compared one with H and A and the other excellent symmetry

http://vimeo.com/album/44212/video/4891812

 

[treasurehunter]

What would be really interesting is to see a video of the same proportioned stones but one Excellent and the other Very Good

 

[smilligan]

What would be really interesting is to see a video of the same proportioned stones but one Excellent and the other Very Good

For symmetry and polish, the difference between Excellent and VG is pretty minimal and would be invisible to the majority of people. It's more of a "mind clean" thing, IMO. The difference between Excellent and VG cut, however, is usually noticeable.

ETA: Here's a good video showing a GIA excellent with AGS 0 light performance vs. a GIA VG with AGS 5 light performance: http://www.youtube.com/watch?v=QJh5SH5fg3I

 

[ChristineRose]

The video pretty confirms what I have been saying for a long time, which is that there is no visible difference between an H&A and a near H&A.

That's not really saying much though. It's like saying you can't tell the difference between light purple and slightly lighter purple. At some point though, there is a difference.

What I'd find interesting is a video with otherwise identical diamonds with symmetry from Excellent to Poor so we could argue about where the point is where the problem becomes obvious. I don't think this will happen though because there probably aren't enough ideal cut diamonds with poor or fair symmetry out there to make a complete set of "otherwise identical" diamonds.

 

[treasurehunter]

Yes christine this is what I'm getting at.
With excellent sym to good sym you can notice quite a difference but with excellent to very good can anyone??

 

[Karl_K]

Yes christine this is what I'm getting at.
With excellent sym to good sym you can notice quite a difference but with excellent to very good can anyone??

If you are talking face up optical symmetry in lighting where it is visible I can and many people can be trained to.
As matter of fact in lighting where it is visible broken arrows or not is the first thing I notice.
Since my eye sight has got bad it isn't as obvious at a distance as it used to be but close enough to be in focus it stands out like a sore thumb to me.

If you are talking lab symmetry ex/id vs VG usually isn't eye visible in RBs but it can be in some cases.
It depends on which facets and lighting.

In the end it all comes down to lighting lighting lighting lighting lighting.
Which are the 5 most important things to diamond performance.
Number 6 being cut.

 

[Karl_K]

btw a diamond can have good lab symmetry and have perfect hearts and arrows.
Several professions who view a lot of diamonds under scopes have reported seeing them.
In theory even poor lab symmetry but I haven't heard of anyone seeing one.

 

[smilligan]

btw a diamond can have good lab symmetry and have perfect hearts and arrows.
Several professions who view a lot of diamonds under scopes have reported seeing them.
In theory even poor lab symmetry but I haven't heard of anyone seeing one.

Hmm. How is that possible? I thought that hearts and arrows were formed by cutting symmetrical facets. Isn't that what lab symmetry grades? I could be way off base here because I haven't done significant research into either subject.

ETA: Per GIA: "“Symmetry” refers to the exactness of the shape of a diamond, and the symmetrical arrangement and even placement of the facets."

Source: http://www.diamondcut.gia.edu/pdf/polish_and_symmetry.pdf



ETA 2: This is interesting: Per WF article on PS: "It is the lower girdle facets that are also responsible for separating the arrowhead from the heart. This is because of the difference between the angles of the main pavilion and lower girdle facets. Therefore, if the physical symmetry is out the slightest, the optical symmetry will be affected. We are not referring here to meet point symmetry which is where the facet junctions meet.

The labs grade symmetry according to meet point symmetry. The physical symmetry is made up of X,Y, and Z-axis which is what influences the optical symmetry. The optical symmetry will clearly show the physical symmetry being in or out of perfect harmony.

The lack of optical symmetry will be seen very clearly when viewing the diamond through the Hearts and Arrows viewer. It is easier to camouflage errors in the formation of the arrows, but it is impossible to hide any inconsistencies in the heart pattern. In forming the arrows there are less facets to align so errors are more easily camouflaged, whereas in the hearts there are 6 facets that complete each heart shape, and the slightest deviation is easily noticed."

Source: https://www.pricescope.com/journal/hearts_and_arrows_diamonds_and_basics_diamond_cutting

 

[kenny]

My understanding of diamond symmetry …

Cut diamonds have sections, or sides.
For instance a modern round brilliant has 8 sides, which can be thought of as 8 slices of a pie.

If the cutter is able to make each of the sides identical to the other sides the diamond will get a top symmetry grade.

Someone please correct me if my understanding is wrong.

 

[pyramid]

I have heard the phrase 'meet point symmetry' that must be what a h&a with vg symmetry is. This is like matching points of facets to
see they are perfectly aligned. I would have thought if the 8 pavillion facets Kenny is mentioning were different widths then the h&a would be all over the place?

 

[Karl_K]

btw a diamond can have good lab symmetry and have perfect hearts and arrows.
Several professions who view a lot of diamonds under scopes have reported seeing them.
In theory even poor lab symmetry but I haven't heard of anyone seeing one.

Hmm. How is that possible? I thought that hearts and arrows were formed by cutting symmetrical facets. Isn't that what lab symmetry grades? I could be way off base here because I haven't done significant research into either subject.

Read here for even more info:
[URL='https://www.pricescope.com/community/threads/symmetry-meet-point-physical-optical.21444/']https://www.pricescope.com/community/threads/symmetry-meet-point-physical-optical.21444/[/URL]

 

[Karl_K]

My understanding of diamond symmetry …

Cut diamonds have sections, or sides.
For instance a modern round brilliant has 8 sides, which can be thought of as 8 slices of a pie.

If the cutter is able to make each of the sides identical to the other sides the diamond will get a top symmetry grade.

Someone please correct me if my understanding is wrong.

That is part of what they grade a huge part of the grade is the meet points.
In your example of pie, how even, strait and uniform and of the proper size the cuts are that divides the pie.

 

[smilligan]

btw a diamond can have good lab symmetry and have perfect hearts and arrows.
Several professions who view a lot of diamonds under scopes have reported seeing them.
In theory even poor lab symmetry but I haven't heard of anyone seeing one.

Hmm. How is that possible? I thought that hearts and arrows were formed by cutting symmetrical facets. Isn't that what lab symmetry grades? I could be way off base here because I haven't done significant research into either subject.

Read here for even more info:
[URL='https://www.pricescope.com/community/threads/symmetry-meet-point-physical-optical.21444/']https://www.pricescope.com/community/threads/symmetry-meet-point-physical-optical.21444/[/URL]

That's a very interesting read. Thank you for posting it. I found the following especially interesting and relevant to this thread: "GIA has concluded that there is negligible visible difference between VG and EX in symmetry and polish. They did find naked eyed experts who could sometimes detect lower symmetry in diamonds receiving Good or lower." This seems to suggest that the average layperson would NOT be able to distinguish between lower grades.

 

[Karl_K]

That's a very interesting read. Thank you for posting it. I found the following especially interesting and relevant to this thread: "GIA has concluded that there is negligible visible difference between VG and EX in symmetry and polish. They did find naked eyed experts who could sometimes detect lower symmetry in diamonds receiving Good or lower." This seems to suggest that the average layperson would NOT be able to distinguish between lower grades.

I take most gia studies like that with a grain of salt because the number of participants are too low and too tilted to older males(the common makeup of the trade) to be scientific.

 

[smilligan]

That's a very interesting read. Thank you for posting it. I found the following especially interesting and relevant to this thread: "GIA has concluded that there is negligible visible difference between VG and EX in symmetry and polish. They did find naked eyed experts who could sometimes detect lower symmetry in diamonds receiving Good or lower." This seems to suggest that the average layperson would NOT be able to distinguish between lower grades.

I take most gia studies like that with a grain of salt because the number of participants are too low and too tilted to older males(the common makeup of the trade) to be scientific.

That's true, but the key word, as I see it, is "expert". In my eyes, that implies that they are trained to identify these differences and if they can only sometimes identify them, how would the average person fair in such a study?

 

[Karl_K]

That's true, but the key word, as I see it, is "expert". In my eyes, that implies that they are trained to identify these differences and if they can only sometimes identify them, how would the average person fair in such a study?

Train a keen eyed youngster what to look for and the will see far more than the vast majority of older males.
I used to be able to see far more before I hit 40 even though I have worn glasses all my life.
Even with bifocals it is not the same as having better eyesight.

Now without training they may only see hmmm something is a little different there and never know its a symmetry issue or may dismiss it as "that's what diamonds are supposed to look like" or they may never see it because they never look for it.
It is really impossible to tell what the average person sees because as soon as you train then to look for something or even ask them to look for something specific they are no longer average. :}

 

[kenny]

I used to be able to see far more before I hit 40 even though I have worn glasses all my life.

Karl, my 50+ year old eyes are crap … but your Octavia still gives me chills, it's sooooo beautiful even out of focus!

 

[smilligan]

That's true, but the key word, as I see it, is "expert". In my eyes, that implies that they are trained to identify these differences and if they can only sometimes identify them, how would the average person fair in such a study?

Train a keen eyed youngster what to look for and the will see far more than the vast majority of older males.
I used to be able to see far more before I hit 40 even though I have worn glasses all my life.
Even with bifocals it is not the same as having better eyesight.

Now without training they may only see hmmm something is a little different there and never know its a symmetry issue or may dismiss it as "that's what diamonds are supposed to look like" or they may never see it because they never look for it.
It is really impossible to tell what the average person sees because as soon as you train then to look for something or even ask them to look for something specific they are no longer average. :}

I like this sentence. So true.