offcenter data on sarin & surface graining

[jin866]

Hi,

Need some help interpret the sarin data.

The diamond I am interested in has the following cut parameters:
table 55.2 (54.8-55.7)
deepth 60.9
crown angle 34.5 (34.1-34.7)
pavillion ange 40.8 (40.5-41.2)
culet 0.1%
girdle 1.4% (0.8-1.
ex ex no-fluor
HCA 1.2
commnet: surface graining not shown

The sarin.pdf also shows offcenter table 0.3%, culet 1% (too big?). Are these offcenter numbers ok considering I am looking for a super ideal. BTW, where can I purchase a H&A viewer?

Another question is regarding surface graining. Is it ok for a VVS2 stone?

Thanks very much,
Nana

 

[Garry H (Cut Nut)]

It probably will not show H&A''s, but should look good in ideal-scope
Dave atlas sells H&A''s viewers - he is listed in top right drop down in appraisers
www.ideal-scope.com for ideal-scopes

The graining is rarely shown as it is usually very hard to see - but can mean drawing an ugly line right across a stones table etc

 

[jin866]

Garry:

Thanks for the explanation. Many sarin reports only contain the parameters and do not have the offcenter graph, is it beacuse of the offcenter is 0% or because people don''t both with it? So I assume it is still a beautiful stone just may not be strict H&A ?

Thanks,
Nana

 

[valeria101]

I am not Garry... May I answer these ?

Date: 5/29/2005 11:15:45 AM
Author: nana

#1. Many sarin reports only contain the parameters and do not have the offcenter graph, is it beacuse of the offcenter is 0% or because people don''t bother with it?

all Sarin graphs have that standard entry... and no it is never 0%, unless by coincidence. I''d expect some number well below 1%. On lab reports, the symmetry grade is lowered if table or culet are missaligned, but this is an unusual and severe fault when it happens, so I would not expect it to be an issue before symmetry gets worse than "good".



#2. So I assume it is still a beautiful stone just may not be strict H&A ?

there are lots of beautiful brilliants that are not H&A. The numbers given say this has as good chances as any of being one.

As far as I know...

 

[jin866]

Thanks, valeria101. I don''t see the offcenter number much, so what''s the acceptable range for ex symm ? Looks like surface graining is still sth need to watch out, hopefully, it is sth at side rather than at the table? Is this stone a keeper? Boy, the more I read, the more confused I am.

Thanks,
Nana

 

[valeria101]

Date: 5/29/2005 6:56:58 PM
Author: nana

I don't see the offcenter number much, so what's the acceptable range for ex symm ?

I do not know what the official tollerance is (if there is one!). The H&A "A cut above" at WF and those at GoodOldGold and Exceldiamonds come with Sarin reports and "excellent" or "ideal" symmetry grades by GIA and AGS. Perhaps someone could guess average starting from these data, but it may not mean much at all. Labs do not deduce symmetry grades from measurements anyway. And you do have the symmetry grade at hand already. Why worry ?



Looks like surface graining is still sth need to watch out, hopefully, it is sth at side rather than at the table?

No it isn't... NiceIce posts some examples of what that graining is - the darn thing is hard to see and allot harder to photograph. I am so impressed by those clear pictures even at 60X.



Is this stone a keeper?
YES


Boy, the more I read, the more confused I am.

Hm... I am not known for clear writing. Really, all those patchy diamond technicals seem meant to confuse. Perhaps someone should advertise diamond cuting courses on this forum !

 

[Garry H (Cut Nut)]

http://www.gemology.ru/cut/english/symmetry/6.htm

If you read down a little on the obove link to where you see the second stone - the one with the photo''s, this is the actual Sarin scan for the stone. Note the culet is more than 1% off center.

ead the full article for a complete explanation.

 

[valeria101]

Date: 5/29/2005 8:00:05 PM
Author: Garry H (Cut Nut)

Note the culet is more than 1% off center.

yeah... is this dependent on the size of the diamond ? More variation appears for smaller ones. Is this: biased sample, measurement problem or deliberate grading allowance !

 

[Garry H (Cut Nut)]

It is a fairly easy thing to measure accurately

read the article Ana

 

[jin866]

Thanks very much, guys. I will try to read those info. But bottom of line, looks like the things about offcenter and graining are nothing to worry about. Ana, your writing is very clear. What I meant is as I know more by reading PS, sometimes I really got trapped by all kinds of minor details.

Nana

 

[valeria101]

Date: 5/29/2005 8:26:08 PM
Author: Garry H (Cut Nut)

It is a fairly easy thing to measure accurately

Depending what "easy" means !