A new polish & symmetry question

[NewShiny]

Hi All,
Well, we''re almost there. My bf has put a down payment on a diamond. My only reservation is that it is rated good polish and very good symmetry. I had my jeweler run a sarin report, and while I don''t have the scores in front of me, he said the stone scored all 0''s.

Is this possible for a GIA graded stone isn''t rated ex/ex to score all 0''s on the sarin? I really like this stone, and just want to make sure I''m getting the right one.

I don''t have all the GIA cert info with me here at work, but the stone is 1.34 F VS2. The rest of the info (measurements, etc.) from from the GIA cert are all within "ideal" range for what I''m looking for. I''ve done my homework on all aspects except for this last issue. Is polish & symmetry really all that important?

I did a search on polish & symmetry here on the forum, but didn''t find anything addressing this particular question.

Thanks!

 

[oldminer]

A Sarin does not score polish and symmetry at all. The most you can get from a pure Sarin report is AGA 0. It takes excellent symmetry and excellent polish to get the other two zeroes. Those are human grades, not graded by the Sarin device.

 

[valeria101]

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On 1/29/2004 2:46:23 PM newslick wrote:



I did a search on polish & symmetry here on the forum, but didn't find anything addressing this particular question.
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These have been mentioned often enough, but rarely (if at all) on dedicated threads. The reason? Neither influences the optical properties (which PS hunts down so fiercely) too much. Thse Ex grades are regarded as some indication of a well-done cut, but are neither required nor suficient to insure a great look for the stone. Stones rated below "good" for either are regarded with suspicion (and not too often encountered), and "good" has become the norm. Rounds are much more often rated VG than any "fancy" cut, so VG could be regarded as more of a requirement for well-cut rounds, esp. in symmetry. Ex? Whatever... why not... there always is enough terrain to hunt perfection, but this may not be essential.

At leats, this ia what I came to learn. There is at elast some mention of symmetry (more rarely polish) issues in the tutorial here, at GoodOlDGold and Preciousmetals, but not a whole lot.

About the GIA cert: if only the specs mentioned there fall between "ideal" proportions, this may mean something but vertainly do not give any indication of optical properties: the variation of the remaining specs is more than enough to give almost any sort of look. Are you getting a Sarin report?

 

[NewShiny]

Yes, the sarin has been run, and I haven't been in to see it yet, but my jeweler said it scored all 0's. If this is the case, its safe to buy, right?

Thanks!

 

[valeria101]

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On 1/29/2004 4:17:07 PM newslick wrote:

Yes, the sarin has been run, and I haven't been in to see it yet, but my jeweler said it scored all 0's. ----------------

Sarin does not "score" anything. The tool produces a set of measurements of the stone and this is all. The jeweler proceded to rank those results against some unknown quality benckmark and pronounced the stone a "0". No idea what he's talking about.

Just in case: this "wording" happens to match the AGS quality groups. One would find a "0"-type cut on AGS certs corresponding to certain measurements of the stone. If you agree with the AGS standards and trust your jeweler to use them righ, why not. At least among the sellers most frequently mentioned on PS, an AGS) cut does not represent top quality, so the price should be somewhat less than whatever an "H&A Ideal" goes for (see the quotes for "known H&As" for reference). The inventory at GoodOldGold is quite a good example: there are AGS stones labeled and priced differently than the "H&A" near them...

All in all: unless the price is not right or the grading is simply an illusion, that should be a worthy diamond - better cut than most of the usual merchandise out there (precisely what the AGS standards were designed to indicate).

 

[elmo]

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On 1/30/2004 2:32:54 AM valeria101 wrote:

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Sarin does not 'score' anything. The tool produces a set of measurements of the stone and this is all.----------------

Not quite so, Sarin and OGI software contains tables of ranges for AGS cut grades and will often output the corresponding AGS cut grade next to each measurement.

The important thing to remember is that the ranges for the zero cut grade are too wide, such that stones with numbers grouped at the low end or high end of the ranges will more often not look as good as stones in what several folks here have called "sweet spot". Of course good looking stones exist across and outside those ranges, sometimes to the point that you wonder "what were they thinking when they came up with this?"

Look at a nice OEC sometime and you'll know what I mean.

One cynical explanation for this is that AGS is a *trade organization* that looks out for its members, so the "ideal" category was created to favor what sellers and cutters wanted to sell, not necessarily what looks the best. Or maybe is was simply a "design by committee" least common denominator sort of compromise. Bottom line is that AGS zero cut doesn't guarantee performance.

Try telling your local jeweler this sometime and watch their reaction

.

 

[valeria101]

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On 1/30/2004 6:49:26 AM elmo wrote:

Not quite so, Sarin and OGI software contains tables of ranges for AGS cut grades and will often output the corresponding AGS cut grade next to each measurement.

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

Interesting... this is new. Does anyone guarantee these grades? I guess any reader of the Sarin report (and here the actual report was not even presented, jut talked about) can add his own "creativity" to the system. Is is always the case, or is it an extra option to incorporate those grades. However, good to know though...

 

[elmo]

It's so common I think it's part of the default view of the data. I don't think that the user can change the tables, probably requires a software update from Sarin or OGI. The cut grade is only as good as the calibration of the machine though

.

Here is OGI report on the niceice site with this info: http://www.niceice.com/certcopies/ags0003651309/ags0003651309msr.jpg

Here is Sarin report on the wf site with this info: http://www.whiteflash.com/hearts_arrows/A-Cut-Above-H-A-cut-diamond-499223.htm#

 

[Jaded Gem]

Hi, here's my two cents. I saw a few diamonds this week. They were all side by side and they all had a great amount of sparkle. One was a .69, J color, very good polish and symmetry. Another one was a .72, H color, excellent polish and symmetry. And the last one was a .72, D color, good polish, and very good symmetry. For some reason both the .69 J and .72 H looked like it sparkled more and the surface looked a lot more polished and reflective than the .72 D. I really liked D's color, but with this brand of diamond one could barely see the little difference of the color contrast through all the fire and brilliancy. Anyway, I talked to another vendor once about polish and symmetry, and he told me that when you get something about a carat or over that someone could see the difference in a good versus very good or excellent polish grade. I didn't know what he was talking about exactly since some other people say that you can't really tell with polish or that the polish isn't a big factor in one's selection if all the numbers are right and all the four C's are great for their diamond. All I know was that side by side, the two diamonds with the very good and excellent polish looked a little bit more buffed or reflective than the good polish diamond. Oh and I noticed this in the .69-.72 range with my eyes and not with a scope. I guess if you could take a side by side view of three diamonds with good, very good, and excellent polish then you may or may not be able to decipher any type of difference. I guess it's all in your eyes and what you see and don't see. I saw the minor difference so the very good and excellent polish stood out a little from the good polish. I hope this helps.

 

[pricescope]

As explained in "On grading the symmetry of round brilliant cut diamonds" today's approach to symmetry grading (used by GIA, AGS, etc) is not good enough to connect symmetry with diamond performance.

Check out also Ideal-Scope' Symmetry page.

 

[NewShiny]

Dear All,
Thank you for all of your responses so far to my posting. I like the debate that is taking place, but hope you can address one of my more basic concerns: how important is polish and symmetry? The general consensus seems to be that it dosen't REALLY matter as long as it is at least "good", the diamond looks great in person, AND the sarin report checks out.

BTW, the sarin report does give scores, and this diamond scored all "0's". Again, I don't have the exact numbers yet (and will post them when I do), but I'm just looking for a nice rock for my ring. I'm not too concerned with the numbers being in the "sweet spot", just somewhere within the acceptable range.

Many thanks,
Newslick