Why can they not just give us a GIA tone, saturation and hue. I mean what does A, AA , AAA really mean or some # value that we have no idea where that # is on the scale.
I hear your frustration and when I asked one very popular vendor that question, he got a bit antsy and he didn't want to go by that scale. He came up with his own grading scale, and I'm sorry, I don't want to have to buy your book in order to figure out your color scale. Ugh!!
I agree, it is so hard to find the information I really want on so many vendor''s sites. I like the vendors to give a description of the color (esp since I don''t know the GIA color scale and I can no longer find it when I do a google search). But a subjective description and than an objective grade that is standard would be the ideal for me.
I know the system isn''t perfect but the GIA Munsell chart is a good starting point where both parties will have at least some sort of colour reference to go by that is in agreement with each other.
The lack of a uniform system is also a great source of frustration for me too
Ideally I''d prefer to have a quantifiable color description AKA GIA Munsell, in addition to something a bit more "romantic" to help those who don''t yet have a well developed idea of what the color grades mean.
The subject of uniform grading criteria has been discussed a number of times on the forum and elsewhere.
There are a couple of problems with out of the box color systems like munsell. First Munsell relies on opaque color chips. Chief among them is the fact that transparent media are capable of a great deal more saturation, can be more vivid than opaque media.
The finest Burma ruby and Mahenge spinel could not be accurately described using Munsell opaque chips. Some, though not all of the problems in GIA colored diamond grading are a result of this problem. GIA uses Munsell color chips.
Not sure if TL is referring to me regarding my proprietary grading system. I try to grade all four Cs and as you know, my approach counts "Crystal" or transparency amongst them. Also my 1-10 overall grade attempts to place the given gem within the universe of the possible or how the stone stacks up against all others and as Harriet notes, the greatest experts can be no more than the sum total of what they have seen.
Richard, for simplicity sake, it would be nice to have a general idea of saturaion and hue based on the color family for the gem. When one is purchasing a Burmese ruby worth thousands of dollars, one would hope to get more information about it from the dealer''s mouth, and additional pictures. However, the GIA system is the one we''re most familiar with, and it does help many of us gage the color of a gem. It may not be perfect, but it''s a standard that many in the gemological profession follow and have absolutely no issues with using. Even if the color changes from axis to axis, that can also be described using the GIA standards.
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