Tough decision [seeking help!]

[Marrior]

Hi there! I'm new to this forum and I'm not exactly sure if this is the right place to ask this kind of question. I'm having a hard time choosing between two different diamond for my ring's center stone. The specs are as follows:

1. Diamond A:
Table:57
Depth: 61.8
Crown A.: 34 degree
Pavilion A: 41 degree
Crown height: 14.5%
Color: F
Clarity: VS1

2. Diamond B:
Table:57
Depth: 61.2
Crown A.: 33.5 degree
Pavilion A: 41 degree
Crown height: 14%
Color: F
Clarity: VS1

Which of the above should I choose? Really appreciate everyone's advice on this! Thanks!

 

[lovedogs]

can you give us more info? Do you have any pics or videos? And what is the ct weight and price? Are they GIA graded?

Neither stone is exactly in the parameters that we usually recommend. For Pav angle, we recommend between 40.6 and 40.8, so 41 is a bit outside of that. For crown, we recommend between 34-35, so 33.5 isn't in that range either. That doesn't mean the stones you asked about are bad, but we would need more info.

 

[bmfang]

Both stones exhibit the shallow crown, deep pavilion relationship so HCA scores should be fine relative to table and depth percentages.

These look to be both GIA graded stones but would need more info about carat weight, dimensions as well as images to make a more informed assessment.

 

[Marrior]

Hi lovedogs and bmfangs,

Both stones are GIA graded. See attached for the pictures

1. Diamond A:

Carat: 1.12
Dimension (mm) : 6.65-6.68 x 4.12
Table:57
Depth: 61.8
Crown A.: 34 degree
Pavilion A: 41 degree
Crown height: 14.5%
Color: F
Clarity: VS1

2. Diamond B:

Carat: 1.08
Dimension (mm): 6.60 - 6.63 x 4.05
Table:57
Depth: 61.2
Crown A.: 33.5 degree
Pavilion A: 41 degree
Crown height: 14%
Color: F
Clarity: VS1

Really appreciate your help!

 

[Marrior]

Based on love dogs suggestion I have found the other two diamonds C and D (below for easy reference) - safe to say that this are better than diamond A and B?

3. Diamond C

Carat: 1.10
Dimension (mm) : 6.58-6.61 x 4.10
Table: 56
Depth: 62.1
Crown A.: 35 degree
Pavilion A: 40.8 degree
Crown height: 15.5%
Color: F
Clarity: VS1

4. Diamond D

Carat: 1.05
Dimension (mm) : 6.47-6.5 x 4.04
Table:56
Depth: 62.2
Crown A.: 35 degree
Pavilion A: 40.6 degree
Crown height: 15.5%
Color: G
Clarity: VS1

Again really appreciates everyone's advice and help! Would love to get the perfect (hopefully) diamond for my fiance

 

[bmfang]

Diamond A HCA results


Diamond B HCA

 

[bmfang]

Diamond C HCA


Diamond D HCA

 

[Marrior]

Hi bmfang, appreciate your quick response! I remember reading something about HCA tools are only good for rejecting 2.0 and above diamond? Thus it's not exactly a good way to gauge which is better?

 

[bmfang]

I was going to post more after the HCA screenshots but was interrupted by my trying to get my toddler to finish his dinner.

All four of these stones score under HCA 2.0 so that is a good start. Garry Holloway would be quite happy with a stone that has low crown angle of 33.5 degrees paired with 41 degree pavilion (after all, he did describe that inverse relationship between crown and pavilion angles to be something that was a good thing from memory).

Am wondering if these stones are listed on Blue Nile.

The main issue is that with GIA graded stones, crown angle rounding is significantly annoying (they round to the nearest 0.5 of a degree) while pavilion angles are rounded to the nearest 0.2 degree. So the stone with the 33.5 crown angle (Diamond B) could actually be anywhere between 33.26 to 33.74 degrees coupled with 40.9 to 41.1 degrees for pavilion.

For me that falls outside of super ideal proportions. Though I do like the chunky arrows (estimating LGF to be 75-76%) of Diamond D (proportions could be within ideal proportions depending on which side of the rounding they actually fall).

I do like Diamond C, again due to the fatter arrows. It’s potentially a safe stone as crown could fall within super ideal/ideal proportions (so 34.76 to 35.24 degrees averaged across all 8 crown angles) as would the pavilion. I don’t have an issue with it being just a tad over 62% depth.

Just my 2c worth.

 

[tyty333]

I like diamond C. Higher crown compatible pavilion angle, shorter lower halfs and nice size table (not too big).
Plus slightly bigger than D.

 

[OoohShiny]

C or D for me - C looks like it might have fatter arrows (shorter Lower Girdle Facets), so with the high crown and smaller table, might be even more fiery than D

 

[sledge]

Hi bmfang, appreciate your quick response! I remember reading something about HCA tools are only good for rejecting 2.0 and above diamond? Thus it's not exactly a good way to gauge which is better?

Yes, the HCA is simply a rejection tool. Basically a pass/fail type grade. Anything less than 2 is worth considering. There used to be a part that stated 1-2 was ideal for rings. 0-1 was ideal for pendants, earrings, etc. And that up to 3 could be considered if precision H&A faceting was in-play.

Essentially the HCA is confirming the proportions of the stone are complimentary. It's an approximation based on data that has been averaged & rounded, so it's not an exact science. Still, it's easier for most folks to plug that data into the HCA calculator instead of having to analyze and understand how the proportions work in relation to each other.

The next step is requesting advanced images. ASET and idealscope (IS) images will provide information on light return performance. I prefer ASET as it tells us more, but many times only an IS image is available. Hearts & arrows (H&A) images confirm the symmetry of the stone. When buying a super ideal stone, all these images are readily available; however, with most vendors offering GIA stones you will be lucky to get an IS image.

This is where it becomes frustrating. As these advanced images help confirm if you should buy or not. If you can't get the images, you have to make a gut call based on the proportions and limited information you do have, and then do an inspection in-person & be willing to return & start over if you aren't satisfied.

 

[sledge]

With the above said, I might point out the following:

• Even in an inverse crown/pavilion relationship, there are limits. I'm not saying stone B with a 33.5/41 isn't workable, but you are pushing the fringes. Between A & B, I'd prefer A.
• But honestly, anytime I see a 41 pavilion I get concerned. I'd want a SARIN report so I could verify the INDIVIDUAL pavilion angles. There are 8 total. If any of those values hit 41.2 or greater, it can be an issue. Those that specifically like and seek out a 34/41 combo is aware this is a slippery slope.
• For the reasons above, I would lean more towards C or D myself. I like the slightly smaller tables and steeper crowns, as they favor a little more fire than brilliance. I also like the fact you don't have the 41.2 pavilion concern.
• What I worry about with stone C is the 35/40.8 combo. Lately, I've seen several stones with this combo and while it falls within the ideal parameters, sometimes things happens that there is leakage that shows up in the ASET and/or IS images. It doesn't always occur, so it's not an automatic rejection but I would want the advanced images to confirm it's not an issue.
• For all the reasons above, my first preference would be stone D. I'd like to see the depth at less than 62, but at 62.2 I don't think it's an issue. I also like the medium 56 table, and the 35/40.6 combo is known to be quite firey.

 

[LinSF]

With the above said, I might point out the following:

• Even in an inverse crown/pavilion relationship, there are limits. I'm not saying stone B with a 33.5/41 isn't workable, but you are pushing the fringes. Between A & B, I'd prefer A.
• But honestly, anytime I see a 41 pavilion I get concerned. I'd want a SARIN report so I could verify the INDIVIDUAL pavilion angles. There are 8 total. If any of those values hit 41.2 or greater, it can be an issue. Those that specifically like and seek out a 34/41 combo is aware this is a slippery slope.
• For the reasons above, I would lean more towards C or D myself. I like the slightly smaller tables and steeper crowns, as they favor a little more fire than brilliance. I also like the fact you don't have the 41.2 pavilion concern.
• What I worry about with stone C is the 35/40.8 combo. Lately, I've seen several stones with this combo and while it falls within the ideal parameters, sometimes things happens that there is leakage that shows up in the ASET and/or IS images. It doesn't always occur, so it's not an automatic rejection but I would want the advanced images to confirm it's not an issue.
• For all the reasons above, my first preference would be stone D. I'd like to see the depth at less than 62, but at 62.2 I don't think it's an issue. I also like the medium 56 table, and the 35/40.6 combo is known to be quite firey.

"MOOOOOMMmmmmm... @sledge is nerding out on diamonds again!"

 

[sledge]

"MOOOOOMMmmmmm... @sledge is nerding out on diamonds again!"

Snitches end up in ditches, lol

 

[Marrior]

With the above said, I might point out the following:

• Even in an inverse crown/pavilion relationship, there are limits. I'm not saying stone B with a 33.5/41 isn't workable, but you are pushing the fringes. Between A & B, I'd prefer A.
• But honestly, anytime I see a 41 pavilion I get concerned. I'd want a SARIN report so I could verify the INDIVIDUAL pavilion angles. There are 8 total. If any of those values hit 41.2 or greater, it can be an issue. Those that specifically like and seek out a 34/41 combo is aware this is a slippery slope.
• For the reasons above, I would lean more towards C or D myself. I like the slightly smaller tables and steeper crowns, as they favor a little more fire than brilliance. I also like the fact you don't have the 41.2 pavilion concern.
• What I worry about with stone C is the 35/40.8 combo. Lately, I've seen several stones with this combo and while it falls within the ideal parameters, sometimes things happens that there is leakage that shows up in the ASET and/or IS images. It doesn't always occur, so it's not an automatic rejection but I would want the advanced images to confirm it's not an issue.
• For all the reasons above, my first preference would be stone D. I'd like to see the depth at less than 62, but at 62.2 I don't think it's an issue. I also like the medium 56 table, and the 35/40.6 combo is known to be quite firey.

Thanks again for the advice everyone!

Hi @sledge! Have attached the images below, for Diamond C from the GCAL report (most readily available information). Not sure which are the one you're referring to? The images looks like there's no leakage (according to my untrained eyes )?

 

[lovedogs]

Are these lab grown diamonds? If so, we aren't supposed to discuss those here, but you can click "report concern" and move the thread to "man made diamonds", where we can discuss them freely. Only asking bc I see the GCAL logo.

 

[Marrior]

Hi @lovedogs oh my apologies didn't realize there's a seperate section for this. Only one of the diamond is nature and the others are man made. Had followed your comment and reported the concern (i.e. Shift this over to the man made diamond section). Thank you! This is such a great forum haha with all the passionate people and detailed advice!

 

[sledge]

So this is a MMD?

In post #4, @Marrior provided confirmation the stones were GIA graded, so I just assumed natural diamonds. But I do see that GIA is offering certs on MMD/lab grown stones.

FYI, as a point of interest -- HPD uses videos shot by GCAL on their natural diamonds. In fact, when I first peeked at this thread, I did a double take to make sure it wasn't a CBI/HPD stone.

https://www.hpdiamonds.com/en-us/diamonddetail/HPD10685



As far as how to answer @Marrior's question about light performance of stone C with the 35/40.8, I am uncertain how to respond. The data provided from the GCAL report is not something I am familiar with; however, the brilliance test appears to be similar to the idealscope. I'm just not sure how it does (or doesn't) directly correlate.

According to GCAL documentation, the more white the better. Blue would indicate leakage.

http://www.diamondid.com/pages/KNOW_YOUR_DIAMOND/diamond_quality/DIAMOND_QUALITY_CUT.html



GCAL's symmetry test appears to be a spin off of arrow imaging. I don't see they offer a hearts version, which we all know really tells the tale about precision faceting. More oddly, they introduce colors similar to the ASET in this image.



I am not certain how to interpret this information, but I do know it's confusing based on more common light performance and symmetry tests available. If by any slight margin GCAL's symmetry image has any correlation to an ASET, then the yellow marked spots may indicate potential areas of leakage. The spot with the star, appears to be the whitest, which on an ASET would indicate the most leakage.

Unfortunately I am just really uncertain how to interpret this image. I'd request actual idealscope and ASET images myself.

Perhaps someone more familiar with GCAL then myself can step in and provide additional analysis.

 

[OoohShiny]

I think DenverAppraiser said in another thread in the MMD section that GCAL 'ASET' images are not ASET so can't be directly compared, but they can be compared with each other.

I think we have to rely on the HCA score to a certain degree with MMDs (and hope the angles of all the facets are pretty accurate) unless it's possible for the vendor to get an actual ASET on the stone!

 

[denverappraiser]

The images on GCAL reports are collectively called 'Direct Assessment Light Performance'. They have two different images that they call 'Optical Brilliance' and 'Optical Symmetry'. They’re similar, and they’re similar to ASET and Idealscope in that they’re all based on reflector technology. The reason they look so different is that the OB image only has 2 colors, the OS has 5, ASET has 4, and IS has 3. I think that has a lot to do with patent protections, which is interesting for people who follow that sort of thing, but it isn't really a diamond topic. Fundamentally, how many colors are there and what those colors are doesn’t affect the usefulness of the tool even though it changes some of the details. That’s why it’s so hard to compare an OS image to an ASET, even of the same stone, and even though both look like something from a Kaleidoscope. The logic is the same, but not the minutia.

The biggest reason I like the GCAL things is that they’ re more controlled. They don’ sell the tools, and don’t provide the info to make your own. I'm sure some smart people could work it out, but if you ever see one of these images, it's nearly certain that it was created by GCAL directly. I don't recall ever seeing a counterfeit. They’re diligent about protecting it, they're very consistent in their approach, and have been for decades. If you’re comparing one GCAL-OS to another, even if they were taken years apart and you got them from completely different sources, you can be confident that you’re making a fair comparison. Every image was taken using the same equipment, by the same people, and using the same methodology. Unfortunately, this isn't always the case with reflector images.

 

[bmfang]

@Marrior , would you be able to provide the GCAL report numbers for Diamonds C & D.

From what I see on those two GCAL reflector images, it’s looking good. Brilliance image for C is showing near perfect light return though the optical symmetry one, like @sledge I am wondering how to interpret the lighter sections in between arrow shafts.

The actual images of the stone at the very bottom (a non-coloured hearts and arrows image) seems to indicate that the stone is cut very nicely. Hearts are consistent and the gaps between the bottom of the hearts and chevrons also look to be the same size.

 

[Marrior]

@Marrior , would you be able to provide the GCAL report numbers for Diamonds C & D.

From what I see on those two GCAL reflector images, it’s looking good. Brilliance image for C is showing near perfect light return though the optical symmetry one, like @sledge I am wondering how to interpret the lighter sections in between arrow shafts.

The actual images of the stone at the very bottom (a non-coloured hearts and arrows image) seems to indicate that the stone is cut very nicely. Hearts are consistent and the gaps between the bottom of the hearts and chevrons also look to be the same size.

Thanks @sledge for the detailed breakdown and sharing of knowledge!

Hi @bmfang, thanks for your effort and time! Have attached GCAL report below (included Diamond A too!), for everyone reference.

Diamond A
https://drive.google.com/file/d/1EScbxwreaxl4Pw4FQw9x6n774s1DtqX3/view?usp=drivesdk

Diamond C
https://drive.google.com/file/d/1-W8VTufPWNgvFKCL02MOQCFLap6GgYLk/view?usp=drivesdk

Diamond D
https://drive.google.com/file/d/1kg5P23FBlUiDcnw5SeVWGyrPXuajnV7W/view?usp=drivesdk

Thank you!

 

[bmfang]

Diamond A, there has got to be one set of pavilions which is sub-34 degrees as the optical brilliance image has gone a prominent dark spot at 6 o’clock. As such, that is out for me.

Diamond C and D are my two preferred stones. I have a slight preference for D as the photomicrographs, particularly in the pavilion side image, the hearts and chevrons are more even than in C. Optical brilliance wise, both of them look to be more or less equal.

 

[bmfang]

Also, are there GIA report numbers for C and D or are the GCAL reports all there are? Was expecting GIA report numbers to have been mentioned on the reports but all there are are GCAL report numbers.

If GCAL, I’m unsure about what rounding is used when they report crown and pavilion angles.

 

[sledge]

For those that may be referencing this thread in the future, I am posting PNG versions of the GCAL certs.

Diamond A - 1.12 F VS1 - 57t/61.8d/34ca/14.5ch/41p
Measures 6.65 x 6.68 x 4.12




Diamond C - 1.10 F VS1 56t/62.1d/35ca/15.5ch/40.8p
Measures 6.58 x 6.61 x 4.10



Diamond D - 1.05 G VS1 56t/62.2d/35ca/15.5ch/40.6p
Measures 6.47 x 6.50 x 4.04

 

[sledge]

Some observations:

Diamond A:
As noted by @bmfang, there is something off at the 6 o'clock position of the optical brilliance image as it's showing up dark (indicating it's not reflecting light at the same rate as the rest of the diamond).

Moving to the optical symmetry image, it appears the diamond is rotated 180 degrees and we now see that same oddity in the 12 o'clock position. This would indicate that white on this particular image is showing a problem with light return.

The photomicrographs (basically black & white H&A pictures) shows us the LGF's appear to be in the 80% range as the arrows are more skinny. Also, there is inconsistency in the chevrons of the heart. When I zoom the PDF version, it looks like a few of the hearts may have irregular clefts as well, but the image is so low resolution it's hard to know with certainty. What is apparent is the heart at the 9 o'clock position is not symmetrical and of the same size of all the other hearts. This is not what I'd consider a true H&A stone.

Overall, I don't think this is a horrible stone but it has a few issues and you have better choices available.



Diamonds C & D:
Of the choices presented, these are the two stones I'd be looking to purchase. As such, I thought a side by side comparison view might be helpful. On the optical brilliance and symmetry images, what I mentioned above is again repeated here -- the light pink areas in the symmetry images are shown as grey areas in the brilliance images.

It's worth noting that in diamond A, the symmetry image had a WHITE spot, which showed up as darker grey in the brilliance photo. On these two diamonds, the only near white spot I see is near the 4 o'clock position on diamond C (circled in orange & appears flipped on the two different images). I previously starred this a few posts back. The remainder of the areas look to be light pinkish.

Perhaps I am trying to draw too much correlation between these and an ASET image, but the light pink almost reminds me of an ASET where we want solid red but get slivers of green inside indicating the stone has some contrast.

Looking at the optical symmetry images, it appears diamond D is more symmetrical. Although I do like the fatter arrows of diamond C, there isn't much variance. I'd guess diamond C to be close to 75 LGF's and diamond D to be 76-77 LGF's. In a non-zoomed view, you probably won't see the variance.

But much to @bmfang's observation, when you switch over to the micrograph (H&A) images the variance in the arrows (LGF's) is more prominent. But more importantly you can see how the hearts image of diamond D is more symmetrical than diamond C. In particular is the chunky chevron on the heart at 12 o'clock on diamond C. Also, zoomed in (again, low resolution) it appears diamond C has some rips in the clefts of the hearts but it's hard to tell for certain.

Overall, I believe diamond D is your winner. It's more precisely cut. It has only light pink (not white) spots. Also, just looking at proportions, that 35/40.6 crown-pavilion relationship is more complimentary.

In regards to the other C's -- the vast majority of people cannot tell ONE color grade of difference. Both are VS1's but we haven't seen the clarity plots to know if anything looks odd there. Things like a knot, or possibly a note that says "grading based on clouds not shown" may alter my opinion. I'm not bothered by the carat weight in the least. Because of weight difference and slightly different proportions, diamond C has a 0.10mm spread advantage. This equals about 1/256th of an inch, which is not really detectable to the vast majority of people's naked eye.

More importantly, diamond D should be priced lower as it's 0.05 carats smaller and one color grade lower.