shape
carat
color
clarity

which diamond to choose?

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kam

Rough_Rock
Joined
Dec 14, 2002
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17
2 diamonds to choose from:

Diamond One:

GIA cert
.76 ct.
VS2 (crystal, cloud)
G
EX polish
EX symmetry
diameter 5.87
crown angle 34.2
pav angle 40.6
culet 0
table size 55.2%
total depth 61.7%
girdle 0.7-1.4
no fluor.
$2890 cash.

Diamond Two:
GIA cert.
.75 ct.
SI1 (broker says is eye-clean)(cert says crystal and cloud)
G
EX polish
EX symmetry
diameter 5.84
crown angle 33.9
pav angle 40.8
culet 0
table size 55.5%
total depth 61.6%
girdle 1.2-1.9
no fluor.
$2600 cash

They seem fairly similar. One has HCA score of 0.8, the other of 0.6, so both have great cut.

Any opinions? Is it worth it to go to the SI1 if it truly is eye-clean (which of course we''d need to verify)? Can the position of a crystal and/or cloud affect the stability fo the diamond or is it strictly an aesthetic effect?

Thanks for your opinions! We''re finally getting close!!!

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Mara

Super_Ideal_Rock
Joined
Oct 30, 2002
Messages
31,003
Hi Kam--both diamonds sound great! Since they are so similar in pricing and other specs, I would definitely suggest to go VS2 if you have not yet seen the stone and will not see before purchasing. If this is an online purchase, for $200 more, why not get extra security with the notch up in clarity? The rest of the specs look so similar, even down to their HCA scores, that the extra bump in clarity would make that decision for me if these are your two final choices.

I don't think you have anything to worry about with crystals and clouds in a VS2...in fact I'd worry much less about them in a VS2 than an SI1, esp online sight unseen. One of the stones we were looking at had a cloud that was visible to my eye slightly without a loupe, it was an SI1. That just made our transition over to a VS1 (would have gladly taken a clean VS2) that much easier...nothing to see with a VS1!
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My 2 cents. Both stones sound great though!
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Rhino

Ideal_Rock
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Joined
Mar 28, 2001
Messages
6,324
That is great advice Mara and my thoughts exactly.

With 2 stones that are cut so closely the next questions that enter my mind are how are the minor facets cut? Only a good qualified appraiser with the right tools could answer this though. The reason I ask is because the minor facets can change the appearance of these 2 stones in a way that could be major to some ... and minor to others. Attached are simulate LightScope images of what the possiblities could be. This is taking the specs of that G VS2. This first example is taking those dimensions and using 43% star length with 75% lower girdle facet length. This is also assuming a very precision cut stone.

If this is what your LightScope image would appear like then this would be a diamond with an emphasis on fire due to the broad bold pavilion main facets (making up the arrows). The pavilion mains (when the crown and pavilion angles are coupled together properly, which in the case of this stone it certainly does) are primarly responsible for strong flashes of colored light. However it will usually take a hit (in a case of such short star/lower girdle combo) in the scintillation department due to what I call "the lack of black" between the arrows. I have a page on my website teaching and showing about all this kind of stuff. Attached in the next post is a virtual model of such a stone too which you can open in the gem reader software which is free and available on this pricescope website.

Rhino

kam01.jpg
 

Rhino

Ideal_Rock
Trade
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Messages
6,324
Here is that same .76ct G VS2 but with 65% stars and 82% lower girdles.

According to GIA's latest research it is these kind of stones that give the greatest DCLR (dispersed colored light return) and I have to agree 110%.

This is a diamond that will have exceptional fire and INCREDIBLE scintillation and brilliancy and are my personal favorites when I am huntin down H&A's althoug most of the finest stuff I find inparticular have around a 60-62% star length.

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Note the presence of blacks at both the arrow heads and arrow shafts.
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Those are like 32 additional tiny mirrors pointing in the face of the observer directing MORE reflection to the viewer. It is a good thing.
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BOTH however are pretty though many have preferences when I have showed both to clients.

There are some who would consider this going too far but when it comes to my hard earned money ... I like to know these kind of geeky things.
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Rhino

kam02star65lg82.jpg
 

Rhino

Ideal_Rock
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Of course there are a plethora of other star lower girdle combo's I could show you but those are 2 types possiblities on either end of the spectrum.

While I was playing I tried shortening the stars down to 60% and with the 40.6 pavilion angle/34.2 crown of the .76ct, the shortening of the stars *with that combo* caused more leakage under the table. Note the pale reds under the table on this pic. Interesting.

Rhino

kam02star60lg82.jpg
 

Rhino

Ideal_Rock
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Joined
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Messages
6,324
Same 60/82 combo but now bringing the pavilion angle to 40.8 instead of the 40.6 and you'll see an image that is akin to many of stones I actively seek out purchase.
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Ok ... sorry for getting carried away.
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If you'd like this kind of info on what you are considering and in the NY area we can look at it for ya however you can also get this from RockDoc. I'm not sure whether Dave delves this deep or not but he may be another source.

night night now.
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Hope this has been somewhat helpful.

Rhino

stars60lg82pav408cr342.jpg
 

Rhino

Ideal_Rock
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Oops... almost forgot the virtual models I was talkin about. Here's the short star/lower girdle combo.

Leonid I think it is GREAT feature that we can attach these gem files. IMO they are really a great educational feature.

Rhino
 

Attachments

  • kayla01gem.gem
    1.2 KB · Views: 21

Rhino

Ideal_Rock
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6,324
Here's the other longer star/lower girdle combo.

Remember you'll need the GemAdvisor software at this link before you can open these files.
https://www.pricescope.com/MSU/gadviser.asp

Kind regards,
Rhino
 

Attachments

  • kayla02gem.gem
    1.2 KB · Views: 20

Mara

Super_Ideal_Rock
Joined
Oct 30, 2002
Messages
31,003
Wow Rhino, busy nite!
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It's fascinating to see the differences small details can make in how a stone can appear to the average viewer. I was never a fan of math, preferring more to read and daydream, but I have to admit, this stuff is very interesting. Guess I should dust off those math skills as I just signed up for the first GIA diamond basics course! Yikes!
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Rhino

Ideal_Rock
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GOOD FOR YOU MARA!!!

I'm not too sure if the current GIA courses get this deep concerning the minor facets but I do know that their research team works alot with Ray Trace software and knows exactly what I'm talkikng about. This is all stuff that'll be on my minor facets page (currently in the works)
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Peace,
Rhino
 
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