Colour Grading

[OldAndMine]

http://www.ruby-sapphire.com/crying-game.htm

I was researching on how diamond colours are graded and I found the above and wonder if any of you who care to comment on what the article has to say?

I am very much an "eye" person come to these things, but then I am an end user and not a trader, so I suppose I don't need to be to caught up in the numbers, stats and gradings, other than to make sure that I am not paying far too much for something priced according to a certain grade system, when buying sight unseen, or, when I am concern about re-sale value or liquidity. In other words, as far as colour go, I am not a "mind colour" person at all.

So the article resonates with me. But I am wondering what the experts might think of it.

If I remember correctly from my physics class many moons ago, a red apple isn't really red, it is only red because our human eyes can only see so many of the actual the physical light properties reflected off the surface of the apple, and that only those ones which we can see with the human eyes, at the exclusion of some others, made the colour "red". If our eyes can see all the wave lengths bouncing off the surface of our "red" apple, then we will never be able to enjoy the prettiness of the colour "red" since it wont look "red". Or, something like that. (Sorry it has been so long ago, this is clear in my mind's eye but I am having trouble verbalizing them, I hope someone who is more knowledgeable can help me clarify this). This realization has also made me rely very little on data provided by a variety of tools measuring light returns.

But then again, as a fan of older cuts, maybe I can get away with these more than fans of round brilliant.

The context of this research in colour grading is my attempt to obtain an Old Mine Cut stone with range of colours which usually fall on the "lower" side, and my attempt to try to understand why antique cuts are usually graded under the EGL system, while modern ones, especially round brilliants are graded GIA, and why the latter is more popular. What I can see from comments in PS is that, this is so because GIA is more stringent in their grading of colour and clarity.

But somehow I suspect, that their differences might be in philosophy rather than stringency of grading. I am not sure. From the article above, it seems to me like the differences in "actual" colours is so minute that the distinction between one grade to another directly next to it can be a bit arbitrary, because so many factors are involved, and there is no guarantee of all of them being made equal. Unless I misunderstood that.

Thanks beforehand for your time!

 

[OldAndMine]

Hi All

Just a quick update and follow up.

I asked for comments on this because I was nervous about an M coloured old diamond ring I was about to purchase. I have never owned anything yellower than GHIJ. And there are such different opinions about colours. Although there are more consensus about older stones. This article made me really think. But I am an amateur. So armed only with my gut (I only saw pictures, which shoes a clear hint of yellow), I decided, nervously, to go for it. And I can't be more pleased. The diamond is old (Old Mine Cut) and it is set in platinum when graded (too fragile to dismount and remount), it is bezel set (I think, in any case the bottom part of the stone is covered) and I took that all into consideration based on what this article said. And the stone look much much whiter than M.

There has been no comments since I last post this, so I am assuming that this article is not way off mark?

I am not sure if this is the appropriate subforum to post this (I am a newbie here). But I thought it technical and educational enough to warrant a place here under the discussion of colour grading?

From my last search of the "Diamond Research" subforum, I have not seen colour grading discussed as much, and I thought this might add some useful info. I hope I am correct?

Thanks again for your time!