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Symmetry and Polish Question

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Heel_Yes

Rough_Rock
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Apr 1, 2004
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Someone please explain symmetry and polish of a diamond to me. Also, please comment on the difference between Excellent Symmetry and Excellent Polish vs. Very Good Symmetry and Very Good Polish?

Thanks
 

Obsessed

Shiny_Rock
Joined
Feb 6, 2004
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104
Symmetry refers to the alignment of the facets and polish refers to the smoothness of the surface.... these two as well as 'cut' are the only things that are controllable by human handling unlike color & clarity.

What does that mean, really? IMO, the most important thing is 'cut'. Its strange that 'cut' is not rated by any certification agency, but it is ultimately what determines the beauty of a diamond. One thing I tend to conclude from polish and symmetry is that they indicate the level of workmanship done by the cutter. An EX/EX rating is the highest of rating and is analogous to say.... a finely crafted automobile, dinner fare by the best chef, or music played by world class pianist. VG is the next best rating and then 'Good' and so on. Although many say that polish and symmetry has a minor affect on the beauty of the diamond and that the difference between Excellent to good is hard to discern, I tend to believe that they speak volumes about the skill and carefulness of the diamond craftsman. It implies what the 'cut' of the diamond would be like. With so many different systems of evaluating 'cut', but no clear rating system, I tend to look at the polish and symmetry ratings to get an idea of how well the diamond is 'cut'. Afterall, all three are the result of one artisan, don't you think? Just so I don't get heat for what i am writing, I'll say that an EX/EX rating DOES NOT gurantee an excellent cut, but i think there is a correlation there. What diamond cutter would spend the extra time and pour such care into producing a diamond with a crappy cut and bad appearance?
 

aljdewey

Ideal_Rock
Joined
Nov 25, 2002
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9,170


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On 4/1/2004 5:39:48 PM Obsessed wrote:










Its strange that 'cut' is not rated by any certification agency,



----------------


What would you call AGS......chopped liver? They most certainly grade cut, and that grading is reflected on their grading reports.

 

Obsessed

Shiny_Rock
Joined
Feb 6, 2004
Messages
104
----------------
On 4/1/2004 5:45:14 PM aljdewey wrote:




----------------
On 4/1/2004 5:39:48 PM Obsessed wrote:





Its strange that 'cut' is not rated by any certification agency,


----------------

What would you call AGS......chopped liver? They most certainly grade cut, and that grading is reflected on their grading reports.

----------------


Chopped liver... very funny. You are right! I stand corrected on that point. But I was thinking of none Round Brilliant shapes, mainly because i was never interested in RBs. Correct me if i am wrong, but there is no cut evaluation system for other shapes, is there?
 

Obsessed

Shiny_Rock
Joined
Feb 6, 2004
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104
Oh one more point,

AGS or HCA? Which is the real authority? Who are we to believe? After watching Mr. Holloway's video, I wasn't sure about using Tolkowsky's ideal(AGS 0). But on the 'other diamond forum', there is that article, 'why HCA(Holloway Cut Advisor?) does not work'. Until the day there is undisputable authority on cut proportions and ratings on all certs, I couldn't truly believe anything but my own eyes.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
17,669
AGS are working on changes to their approach.
One method they are experimenting with uses an instrument like the ideal-scope.
I use the ideal-scope to judge optical quality and symmetry when i buy diamonds. HCA takes too long. but if I can not see the stone - then HCA will work across a very wide range of proportions.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
17,669
BTW we do not have any registration notice from Brad yet to say that he is attending the First Diamond Cut Conference (of which I am one of the convenors).

The head of the AGS lab, and people from the 3 other big labs (except GIA, who are concerned about potential charges of colusion) are attending. So Obsessed we are working on your issue of authoritative agreement.
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Many other authoritative posters from this forum will be attending. All except 1 have been barred from the other site.
 

valeria101

Super_Ideal_Rock
Premium
Joined
Aug 29, 2003
Messages
15,809
----------------
On 4/1/2004 5:58:50 PM Obsessed wrote:


Until the day there is undisputable authority on cut proportions and ratings on all certs, I couldn't truly believe anything but my own eyes.----------------




Right... ony you'd need to see quite allot of diamonds to be sure you are not just selecting the lest bad from a lousy sample !!!!

Authority s usually expressed in price premium... right?
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If you do not believe that, you can also retrace the steps of cut studies behind each and every standard and check the math ! Also, you can alwasy develop your own model, then survey the impact on technical error on the execution of your optimal proportions... All that remains to do is develop a way to measure cut diamonds and make sure what you get is what you want.

Piece of cake
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Fortunately quite a few people spent lots of time doing this already, so all you need is a couple of days to get the hang of it. Fun work
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Besides... unchallenged authority is not exactly reassuring. Is it ?
eek.gif
 
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