Help interpreting CUT from ASET images

[mitrocc]

Hi there,

I've learned so much from reading these forums. I am getting ready to pull the trigger on some type of super ideal cut and would really appreciate some advice for navigating ASET/DiamXray images.

In the 3 examples below from WF, there are two ACA and one expert selection. Looking at Cut only, it looks like the expert selection clearly has some asymmetry and moderate leakage under the table, while the ACAs both seem to have near perfect symmetry and awesome ASET images.

My questions are:
1) How would you differentiate the cut in this category of higher end ideal-cuts and super-ideals? How would you discern which ACA has a better cut?

2) Does this even make a noticeable difference? Specifically, is there even a meaningful difference (defined as >5%) in total brilliance/fire/scintillation between #1 and #2 and #2 and #3, or are we splitting hairs? E.g., there could be a 15% difference (meaningful) between the ES and the ACA, but between ACAs it's a 2% difference (not meaningful)

3) Should the girdle be paler than the table in the ASET images, more intense, or should they be equal? In the examples below, it seems the girdle is paler, while I've seen a more vivid girdle associated with painted girdles leading to a perceived darker table. Is there a rule of thumb or objective way to compare?

Expert Selection:
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-2631634.htm

ACA 1:
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-2813925.htm

ACA 2:
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-2813947.htm


Thanks so much for your advice. At the end of the day, my girlfriend isn't going to care about ASET or Isee2 or Sarin reports but she will notice the way the light moves. I want to try to get her a stone that is a fraction as incredible as she is.

 

[JulieN]

1) ASET should not be used to differentiate between fine cuts. Preferably, you would use your own eyes, but the people at WF will do in a pinch.

You can get more technical details elsewhere, this is a very short answer.

2) WF will probably tell you they are equally beautiful.

 

[mitrocc]

Thanks for your quick response, Julie. I since learned a lot more, and have attempted to reanswer these questions in case it'll be helpful for others:

1) How do you discern which 'super-ideal' has a better cut based on aset/lightscope?

As Julie indicated- Basically not discernible with aset/lightscope alone, which only measures direct light return. In fact, aset/lightscope/gemex only tell that one piece of the story, and n.b. that some diamonds that are designed specifically to ace a particular test, despite performing slightly less spectacularly when outside of those specific and contrived conditions (e.g., solasferas- though they are awesome, are not the hands down winners under ALL conditions that their creator would make them out to be). The best tool to evaluate among super-ideals is probably your eyes.

2) OK, but is there even a *meaningful* difference among super-ideals?

I am an engineer by training, so I ran the numbers, and the answer is yes (imo).

Between the WF ACAs, it is splitting hairs. It seems they are cut extremely consistently with very similar specs. I observed between a 92-95% direct light return (based on 2d area, not technically of total amount of returned light, though the two are very tightly correlated).

However, among various types of 'super-ideals', I did find a reasonable amount of variation in light return. At the top of the scale, is the Solasfera at 100%, consistently. Also the other >>57 facet modified round cuts like eighternity, star129, brilliant lady, etc. generally range from 98-100%. The best unpainted hearts and arrows I've seen max out at around 93-97% (such as this GOG H&A at approximately 97%). I've also seen the GOG AVRs range from 95-99% (which were unfortunately not available in my specs while I was looking). And for comparison, the WF expert selection with table leakage was in the mid 80s, while the rest of diamonds generally fall in the 30-90% range. So there is a difference, even in the high end, but you have to do the math on whether the price difference (if any) is justified and whether the personality of the diamond is something you like (e.g., you can generally get closer to 100% merely by adding more facets, but that does change the look of the diamond).

3) This was a silly question. A lot of my supposedly perceived differences were just due to inconsistent pictures of different stones online. If it were painted or dug out, its AGS/GIA grading would suffer (with the exception of minor to moderate crown-side only painting). If you really wanted to tell, you'd want to look at the actual girdle report or the ranges of it (e.g., thin to thick could be a sign).


And if it would be helpful for anyone- happy to share a dynamic pricing tool that I put together in google docs based on multivariate analysis of bluenile's signature ideal cuts between 1-2.5c to understand the impact on price of various color/clarity/weight combinations, assuming excellent cut. I used it to be able to construct "ideal" combinations and also check fairness when quoted a price by a vendor.

 

[Christina...]

You've been a busy guy! I'll just pretend that I understand how you did the light return percentages. I think that it still comes down to how your eye perceive each cut, for example, in a side by side comparison (video, I haven't seen a solasfera IRL) my eye still prefers the the contrasting and LP of a traditional HA than I do a solasfera. Others obviously disagree hence the success of the line.