Diamcalc result

[lightuser]

Hi,

I'm new to diamond buying and am looking for an engagement ring, probably from Blue Nile. I've been checking dimensions against AGS and GIA ideal standards, and then noticed that a lot of people on here are using DiamCalc to give indications of expected light performance. I tried using the demo, but it doesn't do round brilliant, so I wondered if someone could run these numbers for me, please?

Report: GIA

1.50 ct RB
Diameter 1: 7.28mm
Diameter 2: 7.32mm
Height: 4.55mm
Total depth: 62.3%
Crown height: 15.5%
Crown Angle: 35.5°
Table Diameter: 57%
Pavillion depth: 43%
Pavillion Angle: 40.8°
Culet: None (pointed)
Girdle: Medium to slightly thick (faceted, 4.0%)
Star facets: 50%
Lower facets: 80%

Cut: EX
Polish: EX
Symmetry: VG
Fluorescence : None
Colour: H
Clarity : SI1 (Eye-clean)

If you could explain the results to me, that'd be helpful too, and if you can produce a GemAdvisor file I think I can read that with the demo version of GemAdvisor.

Thanks

 

[Karl_K]

The gia numbers are rounded then averaged then grossly rounded so any model based on them would not be useful.
GIA report does not show optical symmetry which can make a big difference between a model and an actual image.

 

[lightuser]

Oh, that's disappointing.

Is it possible, based on those numbers, to give an opinion of the light performance of the stone? Or is it too hard to make any meaningful statement without seeing it?

Also, does anyone have an opinion about BlueNile?

 

[Brilliantik]

If you are looking at RB the best tool to use would be HCA https://www.pricescope.com/tools/hca you will need Table/depth % and crown/pavillion angles. Anything under 2 is worth checking out.

I ran HCA using the information you had provided and the tools alerted that the girdle is dangerously thin - you do not want this diamond.

Hope this helps.

 

[lightuser]

If you are looking at RB the best tool to use would be HCA https://www.pricescope.com/tools/hca you will need Table/depth % and crown/pavillion angles. Anything under 2 is worth checking out.

I ran HCA using the information you had provided and the tools alerted that the girdle is dangerously thin - you do not want this diamond.

Hope this helps.

Thanks, that's definitely very helpful!

I'm a little confused though about the girdle thickness you mentioned - I ran the HCA and it came out with a score of 2.7 - Very Good - Worth buying if the price is right. Also, the GIA report indicates medium to slightly thick on the girdle. Did I do something wrong?

 

[JulieN]

Must have been a typo.

most people on PS prefer other vendors who provide pictures.

However, if you like one of BN's settings or for whatever reason want to go with them, some new AGS reports have a scan of the diamond that is pretty good. You can use the PS search to filter for AGS.

 

[lightuser]

Thanks again for your help. In the end I decided against it as there were a few things that bothered me (only VG symmetry, subjectiveness of eye-clean SI1) even though I really liked hitting the 1.5 carat mark. My alternative (which I have ordered from BlueNile and will report back on) is the following:

Report: GIA

1.40 ct RB
Diameter 1: 7.18mm
Diameter 2: 7.22mm
Height: 4.41mm
Total depth: 61.2%
Crown height: 15.0%
Crown Angle: 34.5°
Table Diameter: 57%
Pavillion depth: 43.0%
Pavillion Angle: 40.6°
Culet: None (pointed)
Girdle: Medium to slightly thick (faceted, 3.5%)
Star facets: 50%
Lower facets: 80%

Colour: H
Clarity : VS1
Cut: EX
Polish: EX
Symmetry: EX
Fluorescence : None

HCA: 0.8
Light Return: Excellent
Fire: Excellent
Scintillation: Excellent
Spread: Very Good

It looks like this would be the better option (triple excellent, all measurements fit AGS0 (notwithstanding girdle)). I noticed that this also fits very well into H&A range (http://www.heartsandarrows.com/hearts-arrows-diamond-ideal-cut-dna.aspx) - should I expect to see H&A or does this require a particular way of cutting, more than just the angles themselves? Also, is the slight asymmetry (i.e. 7.18-7.22mm top measurement) any cause for concern?

Finally, would you recommend getting the stone loose and then getting it set separately so that I get a chance to better assess it (idealscope, sarin, AGS cert)? I was concerned that it might be damaged by whichever jeweler I get it set with if I go it alone, whereas if BlueNile mess it up I'd wager it's easier to argue?