Q. on diamond and ideal-scope image

[antigoon]

I''ve seen a great diamond on Whiteflash

By the numbers it''s great:
HCA: 1.3 (0.8 - 1.3 if you take the best- and worst-case combinations of crown and pavilion angles)
Table: 56%
Depth: 62%
Crown Angle: 34.7
Pavilion Angle: 40.8
(You can see the full Sarin report on the diamon''s webpage.)

This has the kind of perportions that I''ve found quite difficult to find, especially in an ACA diamond which usually push the limits a little more in terms of getting more size out of the diamond, pushing them closer to ''the cliff''


So I''m quite surprised when I look at its ideal-scope image and it shows lots of light leakage on the outer facets. (Indicating a too deep cut?)

Does the ideal-scope picuture match the numbers? Am I simply wrong about the numbers being so good?

Steve

 

[I wanna rock!]

The numbers look pretty good, but the depth percentage seems high to me. Leakage on the outer facets is common and has to do with the way the upper girdles are cut (I think.) Check www.goodoldgold.com for more info on this. I would be more concerned with the lack of symmetry when viewing the "hot spots" - the black triangular-shaped spots - on the ideal scope image. Again, check www.goodoldgold.com for an explanation of the upper girdles.

This is just my unprofessional opinion.

 

[antigoon]

I thought my reference to my previous post and general content of the post indicated that I''ve got a pretty good understanding of RB analysis. If it isn''t clear for some, let me explicitly add this intro to my post, "I''ve throroughly read all the GOG material, the ideal-scope material (I own one now too), and over the last several months, have surfed most of the posts on this forum, going back to the very beginning. I now have a reasonable understanding of RB proportions." And based on this, here is a diamond that confuses me.

Here''s my reasoning: the crown and pavilion angles look great. But is it too deep? Nope: the HCA score is great and it''s not on ''the cliff''. So it should be a great diamond.
So why does the ideal-scope image show all this light leakage out of the outer facets? Is it ok about the light leakage and will it still look great (just not as big because of this)? Is there an accidental mismatch between the ideal-scope image and the proportions? Is it something else?


Yes, I am also concerned with the lack of symetry as indicated by the uneven size of the hot spots. But that''s not my question.

Steve

 

[Xrisus]

Hey Steve,

I was a long time surfer of Pricescope (for the past 6 months before I bought my rock), so I did tons of research and I came across light leakage questions in my own hunting. I think that your diamond has great specs and a great HCA score. Per the light leakage--maybe this will help (from Garry Holloway''s page).....


http://www.ideal-scope.com/newsletters_issue003.asp


which states:
"Small areas of leakage around the girdle add contrast in the spaces between the star tips.Firey flashes are often from girdle leakage areas, especially in prong set diamonds. Too much girdle leakage makes a diamond look small. A small amount of girdle leakage aids contrast."

I understand your concerns, as when I bought my diamond, I purchased one with minimal/no light leakage on the idealscope. Now on looking back, I realize that girdle light leakage is not an incredibly big deal. I think that in a diamond of your caliber, it will be incredibly hard for your eye to notice the difference between a diamond with little light leakage, and a diamond with no light leakage. I don''t necessarily think that the idealscope or the HCA calculations are wrong or swapped. As you already know, the HCA is an approximation, and doesn''t take into account girdle thickness (which via the "tweaked girdle") is one of the ways that light leakage can be reduced. And this may be one of the unaccounted for factors in the HCA that lead to the idealscope image displaying more light leakage than you expect. But as noted above, I don''t think (in my mind) that it will be a perceptible difference. Good Luck!

 

[Richard Sherwood]

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So why does the ideal-scope image show all this light leakage out of the outer facets? Is it ok about the light leakage
and will it still look great (just not as big because of this)?
--------------

Yes, this stone will look great, and just as big as it should. The outer light leakage you''re seeing will provide a nice contrast pattern along the edge of the stone. The only time you don''t see the outer girdle "triangle" leakage is on stones with "tweaked" girdles, like Eightstar and Whiteflash''s "New Line". Many people like the contrast pattern of the "non-tweaked" stones more than the "tweaked" stones, by the way.

The small spots of light leakage at the end of the star facets are very common, and minimal. In the context of the entire visual presentation which this stone will put forth (outstanding), these small areas of light leakage are no big deal.

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Is there an accidental mismatch between the ideal-scope image and the proportions? Is it something else?
--------------

No, it doesn''t look like a mismatch to me. Both the numbers and the IdealScope image represent a very high level stone in the area of make and light return performance.

The symmetry looks fine to me, by the way. Probably "excellent", or "ideal", depending on who certed the stone. Possibly even Hearts & Arrows.

This is a very nice diamond Antigoon.

 

[strmrdr]

Id like to see the actual heart pics for that diamond.
You might want to email whiteflash and ask for them and post them here.
Also the full sarin file with minor facets would be interesting. Like gog has available.

Another thing to consider is that whiteflash uses brigher lighting than just about everyone so some areas that might be light pink in other pics will look white in their''s.

All else fails call Brian and ask him....

 

[kfds]

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The outer light leakage you''re seeing will provide a nice contrast pattern along the edge of the stone. The only time you don''t see the outer girdle "triangle" leakage is on stones with "tweaked" girdles, like Eightstar and Whiteflash''s "New Line". Many people like the contrast pattern of the "non-tweaked" stones more than the "tweaked" stones, by the way.
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Rich, thanks for that explanation! It helped qualify my experience.

When I picked out my H&A, one of the diamonds I compared it to was a eighternity diamond. Even though I gave the eighternity diamond a slight edge in most lighting conditions, it was when I compared them side-by-side in natural lighting that I was able to pick my H&A over the eighternity. The diamond I went with looked much better to me and it was because of contrast. The eighternity just looked like a "wall of white". Whereas, that may sound good, it wasn''t as pleasing to my eye. ''Til now I still kinda questioned myself because I thought I was supposed to like the eighternity beter since it is a next-gen RB.

I''m glad I went with my eye, but it''s always nice to have some sort of confirmation. Having said all this, I can definitely see how others may have gone the other way and it''s just a matter of personal preference. Realistically, I knew that I was splitting hairs between two excellent diamonds.