DiamCalc Request & Opinions on Round Cut 1.81ct Diamond

[pitbos]

I posted this stone a few weeks ago to poll the community here for feedback. It's coming in at a 1.9 on the HCA. I'm having trouble getting an idealscope image from my dealer and was wondering if anyone here can help run a DiamCalc report for me? Hopefully I have enough information below to allow the DiamCalc report to be run.

I will purchase an idealscope as well, but was hoping to get this report in advance to see if the stone has promise.

Would also like to know everyone's feedback on what they think of the stone.

Thank you all for your continued help in my journey!

Shape: Round Brilliant
Measurements: 7.76 x 7.80 x 4.82mm
Carat Weight: 1.81 carat
Color: F
Clarity: VS2
Cut: Excellent
Polish: Excellent
Symmetry: Excellent
Florescence: None
Table: 58%
Crown Angle: 36.0 degrees
Pavilion Angle: 40.6 degrees
Crown Height: 15.5%
Pavilion Depth:43.0%
Total Depth: 61.9%
Girdle Thickness: Medium - slightly thick (faceted) 3.5%
Star Length: 45%
Lower Girdle Facet Length: 80%
Cutlet Size: None

 

[Garry H (Cut Nut)]

DiamCalc will not provide any extra info. Only misinfo because it will assume perfect symmetry which is not possible in the real world.
the proportions look good and color and clarity are pretty safe, posting the GIA report info on clarity and comments can help us help you.

 

[pitbos]

Really appreciate you providing some feedback. Here is the GIA report. Any further comments/feedback would be greatly appreciated. I am trying to make a decision on this in the next week as they brought this diamond in for me and I'm not sure how much longer they will be able to hold it.

 

[Garry H (Cut Nut)]

no alarm bells

 

[pyramid]

Feather goes through girdle but notice it is VS2? Garry will have noticed that though?

 

[Garry H (Cut Nut)]

Feather goes through girdle but notice it is VS2? Garry will have noticed that though?

Simple to set very close to but not under a prong

 

[pitbos]

Feather goes through girdle but notice it is VS2? Garry will have noticed that though?

Just so I understand, are you thinking it should be graded worse than a VS2?

 

[Garry H (Cut Nut)]

Feather goes through girdle but notice it is VS2? Garry will have noticed that though?

Just so I understand, are you thinking it should be graded worse than a VS2?

Pyramid you know that my view is if a plot looks to good to be true then I would not touch a stone because there will be far worse things than inclusions.
That looks like a regular middle of the road VS2

 

[pitbos]

Very much appreciate everyone's help with evaluating this diamond. I am feeling good based on the feedback and am in the process of negotiating pricing. As a last check, I was able to obtain a Sarin report. I am by no means an expert interpreting the information in this report. How does this look to everyone else? Anything that stands out? Positive or Negatives?

 

[Garry H (Cut Nut)]

You can get my opinion from the top right 'tools' bar and HCA

 

[pitbos]

You can get my opinion from the top right 'tools' bar and HCA

I ran the HCA using the "rounded' values indicated on the Sarin report and I'm getting a score of 2.8. This is a big change from the 1.9 the I originally obtained using the GIA cert. values.

I guess my question is how accurate are the Sarin values? Should they be relied upon?

 

[John P]

\I guess my question is how accurate are the Sarin values? Should they be relied upon?

The Sarin results are actually more reliable than the GIA Report, which averages 8-16 measurements and then further rounds them. The 'actual' PA is 40.7. You can decide how much weight to give the HCA in terms of fine details, but the Sarin data is more accurate.

 

[Garry H (Cut Nut)]

You can get my opinion from the top right 'tools' bar and HCA

I ran the HCA using the "rounded' values indicated on the Sarin report and I'm getting a score of 2.8. This is a big change from the 1.9 the I originally obtained using the GIA cert. values.

I guess my question is how accurate are the Sarin values? Should they be relied upon?

I would expect GIA to have a well maintained and higher accuracy scanner. The 40.65 - 40.78 is really outside the accuracy range of most Sarin scanners. And it may be that the real average is 40.69 with one blip up near 40.78

 

[John P]

Garry, they don't publish any odd tenths for PA. They round to 40.4, 40.6, 40.8, 41.0. Crown angle is more rounded, to the nearest 0.5. Stars and LH to the nearest 5%. So even when PA average is truly 40.7 the GIA will never ever say 40.7.

 

[Garry H (Cut Nut)]

Garry, they don't publish any odd tenths for PA. They round to 40.4, 40.6, 40.8, 41.0. Crown angle is more rounded, to the nearest 0.5. Stars and LH to the nearest 5%. So even when PA average is truly 40.7 the GIA will never ever say 40.7.

Of course John, but what I mean is the GIA scanner will more likely decide if this stone is 40.6999999 or 40.70000001

 

[John P]

Of course John, but what I mean is the GIA scanner will more likely decide if this stone is 40.6999999 or 40.70000001

Which goes back to your comment about accuracy. Roger that.

 

[gm89uk]

I was under the impression that any odd numbers are always rounded up. So a GIA report of 40.6 pavilion would mean a theoretical range of 40.5-40.69, and 40.7 would go to 40.8.

So it is interesting that the sarin report should correlate to a GIA pavilion angle of 40.8 (as is highlighted in the facetware GIA Cut rounded value). Is this what you guys are referring to above? That the GIA scanner may actually have calculated a rounded value <40.7 and the sarin just above, causing the discrepancy?

 

[Garry H (Cut Nut)]

I was under the impression that any odd numbers are always rounded up. So a GIA report of 40.6 pavilion would mean a theoretical range of 40.5-40.69, and 40.7 would go to 40.8.

So it is interesting that the sarin report should correlate to a GIA pavilion angle of 40.8 (as is highlighted in the facetware GIA Cut rounded value). Is this what you guys are referring to above? That the GIA scanner may actually have calculated a rounded value <40.7 and the sarin just above, causing the discrepancy?

GIA round up and down arithmetically - so as i stated 40.6999999 = 40.6 and 40.70000001 = 40.8. Exact 40.70 is very rare - I am not sure how they handle that. If I were making the decision I would round toward a better cut grade if the symmetry is better and toward a lower cut grade if the symmetry was worse.

 

[pitbos]

My Idealscope arrived the other day and I've had a chance to photograph the diamond. Here is a photo of the 1.81ct stone (apologies for my poor photo but I was using a point and shoot camera):



And another photo:



What are everyone's thoughts?

 

[Garry H (Cut Nut)]

Its a keeper.
and very nice symmetry.

 

[Karl_K]

Its a keeper.
and very nice symmetry.

yep
Nice job on the IS photos.
If you want to remove the tint try a different white balance setting on your camera.

 

[John P]

Sidebar. Pitbos, pay no attention to this

and very nice symmetry.

In my best Texas accent...

Well golly Mr Holloway that ain't no news. The ol' GIA report said "Symmetry Excellent." Just scroll on up and see.

I even searched it up. Didja know that-thar symmetry in the lexicon of diamond-grading is just a surface inspection of facet meet points, crown-pavilion twist and broad measurement swings? Heck, my GIA bible even says grading of polish and symmetry must be done in-person. Since I don't reckon you seen this diamond you had me a-scratchin' my head...

Then I said "hold on JP!" That Cut-Nut hombre isn't loco. I bet he's talking 'bout optical-precision, which is the modern term for fine 3D internal facet-alignment capable of producing bolder optical events and such!

Heck. That ain't no symmetry... Symmetry's all on the surface, like skippin' a rock 'cross the pond down in the holler. Optical-precision's what's in the water, like divin' in, catchin' fish and findin' treasure. Yee-haw!

Yep. I reckon Mr Holloway meant him some optical-preecision. But he's a busy feller. Plus he's the sheriff 'round these parts. Now let's go find us some treasure! (shoots guns in the air)

*
Sidebar over.

 

[pitbos]

I can't tell you how much I appreciate everyone helping me with this. I've been searching for the right stone for around 6-8 months and I feel extremely relieved that you feel this is a quality stone. Finally I can make a purchase! The girlfriend will be very happy...finally!

On a side note, here is a photo of the stone that I was debating between. It was either the 1.81ct above or this 1.77ct (both round brilliants). The ideal scope helped me reject the 1.77ct stone. I think the 1.81 is much better based on the IS.

 

[Garry H (Cut Nut)]

Sidebar. Pitbos, pay no attention to this

and very nice symmetry.

In my best Texas accent...

Well golly Mr Holloway that ain't no news. The ol' GIA report said "Symmetry Excellent." Just scroll on up and see.

I even searched it up. Didja know that-thar symmetry in the lexicon of diamond-grading is just a surface inspection of facet meet points, crown-pavilion twist and broad measurement swings? Heck, my GIA bible even says grading of polish and symmetry must be done in-person. Since I don't reckon you seen this diamond you had me a-scratchin' my head...

Then I said "hold on JP!" That Cut-Nut hombre isn't loco. I bet he's talking 'bout optical-precision, which is the modern term for fine 3D internal facet-alignment capable of producing bolder optical events and such!

Heck. That ain't no symmetry... Symmetry's all on the surface, like skippin' a rock 'cross the pond down in the holler. Optical-precision's what's in the water, like divin' in, catchin' fish and findin' treasure. Yee-haw!

Yep. I reckon Mr Holloway meant him some optical-preecision. But he's a busy feller. Plus he's the sheriff 'round these parts. Now let's go find us some treasure! (shoots guns in the air)

*
Sidebar over.

A couple of weeks in Euroep seems to sharpen your mind Sir John.
It is possible to measure both without human observers now.
What you are referring to is the optical sym, and that is measuarble by using a regular scanner to a very highe degree - much more so than a human with a microzcope - the part we worry about at least.
http://www.octonus.com/oct/products/helium/polish/ the reports from Helium Polish are amazing and have contributed to a lot of manufacturing improvements.
A new system uses reflected light from known sources to identify facet meet points. Patent is about 10 years old.

 

[John P]

A couple of weeks in Euroep seems to sharpen your mind Sir John.
It is possible to measure both without human observers now.
What you are referring to is the optical sym, and that is measuarble by using a regular scanner to a very highe degree - much more so than a human with a microzcope - the part we worry about at least.

Don't mind you to say "optical symmetry." But standing alone, the word symmetry means something else.
Of course you know that I know that you know all of this Garry. Just pulling your tail - and making a PSA. For the record, AGSL is now using the term Optical Precision.

RE: "regular scanner," I don't consider Helium regular. Does it remain more precise than Sarine HD ond Ogi? DiaMension's given error remains ±0.1° angular, ±10 microns linear. Their other scanners still publish error that's 2X as wide.

So when you say "it's possible to measure both" we're not seeing panacea yet. In fact we regularly see inaccuracies in the scan-simulated ASET imprints published on the AGSL Dual Platinum Reports we use. While slight, many are undeniably less precise than what we see if we view the diamond in a live ASET scope. Sometimes they're off-enough that we request the lab to re-do the scan entirely.