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"Apparent colour" differences between facet pattern types

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
21,105
I have a question from the discussion that came up in my other thread on precision cutting here, that I'd prefer to ask in a different thread so as not to derail that one.

Forgive my lack of eloquence - but here is my scenario: I give a cutter three lumps of rough, identical in every way except colour. One is fit for a 1ct I, the second for a 1ct K, the third for a 1ct M. I ask the cutter to cut each into a 1ct RB worthy of the GIA EX grade (so using those specific known constraints) that best "evens out" the "apparent colour" differences - so that when you look at each stone face-up in diffuse office light, they look to be the same slightly tinted colour (like the way FCDs are graded by apparent face-up colour, which a cutter can manipulate).

1. Is this *possible*?
2. What would be the cutter's best choice - and maybe Diagem if you will indulge me here, since you so kindly invited questions in my other thread ::) how would you choose, and how would you verify your choice?


My first instinct is to advise cutting the M into an RB w/ large table, as shallow crown/pavilion combo as I can get away with within the GIA EX constraint, very thin mains, thin girdle plus paint the crown - again, as much as I can get away with. Because my GIA H with such proportions was much *whiter* to my eyes than my other GIA H of similar size w/ short lgf, higher crown, thicker girdle...

BUT, at some point on that D-Z spectrum smaller virtual facets spitting out splintery little coloured low-energy twinkles result in colour saturation rather than colour minimization... or, at least, that's how I understand it. Where is that line? Is it predictable? Does it change from person to person? I know that the discrepancy in apparent colour face-up between an H EightStar type RB and an H radiant designed to highlight colour would be far less than the face-up apparent colour discrepancy between a Y/Z EightStar and a Y/Z radiant designed to highlight colour, thanks to the increase in absorption w/ every incremental increase in path length. And I saw last year that to my eyes a J emerald cut showed more body colour face-up to my eyes than a J AGS0 3chevron princess of similar weight, while a gorgeous chunky W/X OEC showed far less colour face-up than a slightly smaller S/T radiant - but obviously these are different design patterns, so it could be comparing apples to oranges - or to elephants. Too bad they didn't have an S/T AGS0 princess, that would've been enlightening!


Rhino I see that GOG has a couple of 1.2ct R AVRs and a 1.26 Q H&A RB - would share your thoughts on which, in your opinion, faces up "whiter" - in what types of lighting? I would be really interested to hear what you think. What about your K/L/M AVRs and H&A RBs?
 
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