Talk:Diamond clarity

message: Diamond clarity is graded on a scale from FL (flawless) to I (imperfect).
The standards for each grade are based on how "obvious" or "difficult" it is to see imperfections at various magnifications, such as 1x (with the naked eye), 10x, or 30x.  While on-line brochures give the magnification, they do not specify the distance between the eye and the stone.  Is this 3"? (Probably not -- many people cannot focus this close.)  Is this 6"? (Similar problem.)  14"? 15"? 21?  Note that there is 3x magnification between 7" and 21". 
Do any of the major grading labs (such as GIA, AGS, or HRD) have a standard on this?  For that matter, several U.S. Military specifications (such as for surface defects in ceramics) have similar wording.  Do the mil specs have a standard eye-to-object distance?
:As far as I know, no. While I don't work for any of the labs you mention, I think I would have heard about such a standard. Nowadays most labs use custom microscopes for grading stones, so "distance to eye" doesn't come into play. A grader has to be careful not to scratch the objective lens with the stone, of course.
:When a loupe is used, both it and the diamond are usually held fairly close to the eye as a matter of practice. When checking the stone with the naked eye (especially in unclear cases to judge whether an inclusion justifies a grade of I1 as opposed to SI2) a grader's astigmatism (or lack thereof) will determine distance from the eye. Although I'm fairly myopic and therefore I might be able to see closer, if I can see the inclusion the stone is automatically graded at least I1. (Visible to the eye means visible to the eye.) Some labs may assign an SI3 grade in debatable cases, but of course not everyone recognizes this grade.
:Some labs are looser than others when grading stones, but that's not something I should get into here. I try not to be a mudslinger. ;) -- Hadal 04:30, 3 May 2004 (UTC)
replies: text: I realize that this thread is a few years old, but I think a major misunderstanding is apparent here. Clarity grading has VERY LITTLE to do with eye-cleanness. Clarity grading has everything to do with what the stone looks like under 10X magnification. Eye-cleanness can occur in the I1 (a stone that has a very extensive cloud may not be apparent to the eye - but still be graded I1), an large emerald cut diamond with a small solitary EYE-VISIBLE inclusion in the corner of it's table, may still be graded VS2. Eye-visibility should never be used as a defining criteria for clarity grade. With this in mind, the distance to the eye is irrelevant. SauliH 21:03, 4 February 2007 (UTC)
thread_title: How clarity is judged

message: :That said, I did chuckle at this line from their site:
::"Without the proper instruments and education on what to look for, consumers can easily misread a diamond’s clarity."
:That may be true of the upper grades, but a savvy consumer should have no trouble spotting an I1, as the fellow in that DiamondTalk thread did. In my rather cynical opinion, I think sellers who use half a yard stick (for crying out loud!) to determine "eye visible" are trying to pass inferior stones off at higher prices than should be paid for them. And that bit about the culet was misinformation. A "medium" culet will detract from the final grade of the stone, or at least it should. As would a lack of culet in a large stone.
At diamondregistry.com they reference eye-clean in terms of the concept of "Relief": The color of the inclusion can cause it to stand out in high relief against the background reflections of the diamond. In a near colorless diamond, a black crystal is easier to see than a white one. 
If the diamond is not "eye-clean" then it is evaluated using a 10x loop to assess its clarity.  —Preceding unsigned comment added by 50.8.12.252 (talk) 05:53, 6 February 2011 (UTC)
thread_title: "Eye clean" vs. Imperfect

message: :As for your comments on the microscopes, of course there is a consistent distance for best viewing. I don't think I understand what you're asking; maybe I'm daft, but how can a standard distance be applied to microscopes in this case? There are no great differences in the length of the optical train in the various models used (I've used at least three different makes). The distance from the stone and the objective lens would be determined by the magnification level. The only feature a microscope must have is a 10x setting (and, to be thorough, overhead lighting and darkfield illumination). Or am I missing something? -- Hadal 14:20, 10 May 2004 (UTC)
thread_title: What is 10x relative to?

message: The current debate about cut-grading standards involves explicit assumptions about lighting and the distance at which a diamond is viewed.  The choice of 10 inches versus 14 inches explains some significant differences between two proposed grading standards, according to this PriceScope thread.
By the way, the stone in the contentious DiamondTalk thread was graded by the AGS as an SI2.  Perhaps large SI2 stones do not need to be eye-clean?
-- Jasper 20:15, 14 May 2004 (UTC)
thread_title: A couple of tangents

message: I have been looking for references to the history of the development of clarity grading which I have read somewhere - especially the GIA system. I am sure it was online. Does anyone know a link to this, as it would greatly help to expand this article. Other subjects that should find mention here is that the GIA system was developed for trade use (especially in the DZ color grade system). I wish I could find the source I need for this, it is not in my GIA course material, but I remember reading it somewhere. SauliH 15:48, 7 December 2006 (UTC)
thread_title:  History of clarity grade development 

message: The removal of links to the websites of EGL, GIA seems add. Gwernol asserted that these violate WP:EL policy, but has not given a reason why he removed after a revertion was made. Please explain. SauliH 15:51, 7 December 2006 (UTC)
thread_title:  Deletion of EL's