Two very similar stones- visual difference possibility?

[pfunk]

I am hoping some of the experts here may be able to shed some light on what kind of visual differences you might expect to see in two very similar stones with very slight differences in their uppers. Here are the specs on them:

Stone 1-
1.79c - 7.76-7.79-4.82 mm
Table- 55.4%
Total depth- 61.9%
CA- 34.6 (15.4%)
PA- 40.7 (43%)
Star- 53%
LG halves- 79%

Stone 2-
1.813c - 7.78-7.82-4.83 mm
Table- 55.9%
Total depth- 61.9%
CA- 34.9 (15.4%)
PA- 40.7 (43%)
Star- 49%
LG halves- 79%

Assume both have very good optical symmetry, though the lower girdle halves prevent H&A designation due to clefts in the hearts.

Is there anything that can be concluded about possible visual difference going solely off the report numbers?

Is there more potential for fire in the stone with a slightly larger crown angle?

Is there a preference for either shorter stars and steeper crown or longer stars and shallower crown?

Is the probability very low that someone who is new to diamonds will even see a difference?

 

[marymm]

IMO, yes, the probability is very low that there will be a readily apparent difference between these 2 diamonds, assuming both are GIA/AGS graded.

 

[pfunk]

Yes, they are indeed both AGS graded. If they were not, I wouldn't even pose the question due to the rounding of numbers on GIA reports. But with AGS grading, I figured more conclusions could be made thanks to the more exact measurements in an AGS report. I know there can still be issues due to the the averaging of the angles, but I am under the impression that a good hearts pattern would indicate high precision and relatively small differences in the angles. The IS and hearts images of the stones look very similar, and with such similar numbers I anticipated the visual differences would be hard for an inexperienced consumer to detect. Still, I thought the experts may be able to shed some light on how a small difference in table and upper angles could contribute to a slightly different look.

 

[KobiD]

Its my understanding that the steeper crown angles tend to produce more fire. Taking that a step further though, the star facet length and table also effect the angle of the upper girdle facet. Looking across the figures I'd guess that they'd both balance out quite well. Which one is cheaper? Best colour? Inclusions?

If they're through the same vendor you could always ask for a gemologist to give you an opinion after a visual inspection.

 

[pfunk]

Thanks for the responses. Actually these are from different vendors but one I have in my posession and hope to do some very close inspection on tomorrow. They are equal in color grade, but the one I have is a VS1 vs an SI1. For reference, my stone is the 1.79 which I have posted in some previous threads as well. Mine is non branded, while the 1.81c is branded and is therefore about 1.5k more expensive.

I have been doing more reading about how indexing while cutting the upper girdle facets affects their angles. From previous threads in which John and Karl have discussed stars, it sounds like the upper girdle facet angles are more important than the stars.

To my knowledge, though, the upper girdle facet angles are not shown on AGS grading reports?

I found an AGS publication about the effects of indexing upper girdle facets which contains some sample ASET and Ideal scope images showing what the different indexing options will look like. In the process of digesting all that information now and will try to see if this could be a possible difference between the stones that the grading report will not show.

 

[KobiD]

The length of the star directly affects the length of the upper girdle. Some number crunching in order. In saying that, do you think you'll notice such subtle details, or are you specifically looking for a certain type of performance?

 

[pfunk]

Kobi, actually I am guessing I wouldn't be able to see a visual difference between the two since I am far too inexperienced to pick up on subtleties. But since I can't get both stones in my possession to examine them side by side, I figured I would ask those far more experienced than I if a perceivable difference is even likely based on numbers alone.

After one of your threads, I got a little concerned as to why the vendor would have chosen an AGS report without the ASET image. So I started to think about what could have been different on my stone that would have detracted from its performance and/or marketability and that would have been revealed on an ASET image. So I figured I would try to find stones with very similar proportions that were accompanied by ASET images, so I would at least know what mine should look like. This led me to more closely examine the process of cutting the upper girdles and stars, and ultimately to the indexing of the uppers (classic vs painted vs dug out).

I noticed that the whitefish ACA and expert selections tend to have very similar proportions to the stone I purchased, with the exception of the LGF. Mine seemed to have most in common with the expert selections which seem to miss the ACA often times because of LGF being too long. I could be completely wrong about that, but it is a pattern that I seemed to notice.

Ultimately, after all of the reading and examining images that I have done, I'm pretty confident there is no way for me to know (or perhaps for others to speculate) how they may compare visually without actually seeing them in person, which just isn't going to happen. I am, however, quite confident that there is no digging or painting going on after closely looking at the ideal scope which is reassuring.



While the branded stone may indeed look better visually to the well trained eye, I am not sure I would be able to see the differences. The similarity between the proportions, ideal scopes, and hearts view have convinced me that I likely wouldn't see the difference.

From everything I have read though, the super ideal cuts do not happen by accident and you aren't going to find, at random, a super ideal cut in random inventory. Not to say that the stones I am describing are the super ideal, because they are not. From what I can tell, they are better than most, but not the very best. It wasn't in my budget to pay for the very best of the branded stones, but it still seems that what I ended up with is better than most and it doesn't appear that I overpaid for it which is comforting.

 

[JulieN]

I already told you to stop worrying about your gorgeous stone.

I think the AGS reports that have an ASET picture are more expensive. Maybe the manufacturers didn't want to pay for the upgraded report if they weren't going to sell the stone at a big premium.

 

[pfunk]

I already told you to stop worrying about your gorgeous stone.

I think the AGS reports that have an ASET picture are more expensive. Maybe the manufacturers didn't want to pay for the upgraded report if they weren't going to sell the stone at a big premium.

Thanks Julie! I have a mind that never stops going so I can get a little OCD at times. Especially when it involves math/geometry and feels like it should be easily explained by the angles and measurements. I have spent FAR too many hours educating myself on diamonds, but have found it quite fascinating and feel like my interest in them will likely grow and persist.

It is a very pretty diamond, and I look forward to posting some show me the bling shots in the near future!

 

[KobiD]

Seems we're very much on the same page pfunk with where our thoughts have been taking us.

To me it seems simple! The very best light performance and symmetry comes with a premium price tag, and all the vendors know their stock! Buying from the 2nds batch (ideal rather than super ideal), is a good compromise in terms of value vs performance! Its easy to chase stoned which may/may not be better, so a simple question to ask is.. does the stone you have sparkle and look beautiful to you? If so, thats the main thing!

If the IS image below is the stone you have, you should be stoked! Just my opinion.

 

[pfunk]

Seems we're very much on the same page pfunk with where our thoughts have been taking us.

To me it seems simple! The very best light performance and symmetry comes with a premium price tag, and all the vendors know their stock! Buying from the 2nds batch (ideal rather than super ideal), is a good compromise in terms of value vs performance! Its easy to chase stoned which may/may not be better, so a simple question to ask is.. does the stone you have sparkle and look beautiful to you? If so, thats the main thing!

If the IS image below is the stone you have, you should be stoked! Just my opinion.

It does look beautiful to me, and I am sure she will be thrilled with it. It would be nice to be able to sit down and look at the best cut from each vendor and see if you can really tell a difference. I am sure you can, after you gain some experience in what to look for, but for now I will just have to be happy with something not quite super ideal. Which I am, because it comes at a significant discount over the super ideals. And yes, that is the IS image from mine and it is indeed quite lovely!