General Diamond Performance: Vendors please

[sleeprequired]

can a mod please remove this thread from the diamond research section, i think i posted it in the wrong section.

lets assume i have 2 diamonds H&A cut equally precise... i wan't to know 'theoretically' how both will perform and i know the HCA doesn't take into account the star and lower girdle lengths which would be a potential game changer of course...

so these dimensions are for two stones. Can you please explain the the different 'personalities' of the stones. I am aware after watching a few videos for most eyes these differences are minimal.

So the main differences here are the table %, Pavillion angle, Star & lower girdle. One rates excellent except with VG spread (stone 1) on HCA and the other excellent for light return and very good for the rest (stone 2). Given that the HCA doesn't factor in the stars and lower girdles does that mean that stone 2 could perform as well (or better) as stone 1? Theoretically.

Stone 1
Depth % 61.5
Table % 55.4
Crown Angle 34.8
Star 51.0
Pavilion Angle 40.7
Crown % 15.4
Lower Girdle % 79.0
Culet Pointed

Stone 2
Table %: 54.6
Depth %: 61.6
Crown %: 15.6
Crown Angle: 34.8
Star %: 53.0
Pav Angle: 40.9
Pavillion %: 43.1
Lower Girdle %: 78.0

 

[John P]

lets assume i have 2 diamonds H&A cut equally precise... i wan't to know 'theoretically' how both will perform and i know the HCA doesn't take into account the star and lower girdle lengths which would be a potential game changer of course...

In addition to no star or lower half information, the HCA takes a single number to represent CA and PA. But there are 16 separate measurements for those angles, which are averaged and (on GIA reports) rounded up or down...in the case of CA to the nearest 0.5 degree. The HCA treats them as single data points.

What it's doing is taking averaged 3D numbers and drawing the most elementary 2D "chalk outline" to indicate in the broadest sense whether the primary angles - averaged and rounded - are promising or not.

With that said, the HCA is a great tool, but don't read more into it than is possible.

So these dimensions are for two stones. Can you please explain the the different 'personalities' of the stones. I am aware after watching a few videos for most eyes these differences are minimal.

There is no way to tell from numbers. On paper they are extremely close. In real life and 3D it's likely they will be close, but without knowing cut consistency we can't say. You said "cut equally precise." If so, and that precise cutting is close to the averages you've cited, flip a coin. The primary numbers are so close that it would be a challenge for anyone, even the cutters, to tell the difference.

So the main differences here are the table %, Pavillion angle, Star & lower girdle.

Not so much. They are so similar as to be negligible. Unless, as mentioned, there are differences in cut consistency and the independent measurements (there are 16 separate measurements for lower halves) stray notably from the cited averages.

 

[sleeprequired]

Thank you for assisting John. Ok so i've done some reading and I understand what you're saying about the cut. What would a person ask for to be able to more accurately determine the min-max upper and lower girdles or indeed every one to accurately assess the cut?

If i understand you correctly the smaller the range the more precise the cut even though they both achieve AGS Ideal across the board.

 

[Lula]

Thank you for assisting John. Ok so i've done some reading and I understand what you're saying about the cut. What would a person ask for to be able to more accurately determine the min-max upper and lower girdles or indeed every one to accurately assess the cut?

If i understand you correctly the smaller the range the more precise the cut even though they both achieve AGS Ideal across the board.

A Helium or Sarin report will give you more information about the exact (rather than averaged) dimensions of the stone. Look for a vendor that provides this information on their stones.

 

[John P]

Thank you for assisting John. Ok so i've done some reading and I understand what you're saying about the cut. What would a person ask for to be able to more accurately determine the min-max upper and lower girdles or indeed every one to accurately assess the cut?

Request an ideal-scope or (preferred) ASET image. If the diamonds are being advertised at H&A request H&A images.

If i understand you correctly the smaller the range the more precise the cut even though they both achieve AGS Ideal across the board.

Yes and no. In a theoretical wire-frame world, yes. In that sense having the numbers for every facet would give you a "checklist" but it may or may not be decisive. Scanner error is a fact of life. And beyond that it's possible for skilled producers to make optical adjustments beyond the basic numbers: A boutique cutter committed to 3D precision might experience some give and take and still produce a completely robust optical (3D) performance result. Diamond is the world's hardest substance. Routinely we find that certain facets may not "run" as well as others. A dedicated cutter can work so that opposite facets average correctly to preserve the appearance - in real life as well as precision-viewers. But this is pretty rare territory. No labs require such tolerances to acquire a top grade so it's certainly not done in mass-productions, unless it's a happy accident.

 

[sleeprequired]

Ok so i've got some of the images below for stone 1...

on this page about 1/2 way down under the heading 'star facets' there is a comparison of 2 diamonds.. i'm trying to get one more like the first one with 65% stars and 80.6 lower girdle in terms of fire and scintillation. While the angles of stone 1 are different (51 stars and 79 lower girdle) i think it's very close in terms of the spots that are showing the fire and scintillation under the heading 'lightview #1 with diamond'. Hope i'm making sense...

i also noticed in the ASET image some of the arrow are blue instead of black... any other comments appreciated.

 

[Christina...]

Nice black stars and black on the arrow shafts. Looks like a beautiful diamond and you should get some nice displays of fire. But I'm no John Pollard so its a good this g hes here.

 

[sleeprequired]

so my understanding is once you've got the nice black stars and the black near the arrow shafts that means you will have good fire and scintillation.

so if the IS and ASET is showing you that it is doing so because of the lower girdles, stars, crown and pavillion angle. So once you see those then it doesn't matter if you've got 51 stars and 79 lower girdle or 55 stars and 77 girdle for instance - you're going to get that fire and scintillation because of what you're seeing...

 

[Gypsy]

Once you post the ASET I'm not certain John can respond within forum rules. That's why I said avoid spefic stone stuff. Because, once again, he can't comment on competitor stones. If he can't comment then ask the moderators to delete that post of your with the ASETs.

 

[sleeprequired]

right i thought it would be ok without a specific link but obviously not... i have let them know ...

 

[Gypsy]

right i thought it would be ok without a specific link but obviously not... i have let them know ...

Nope. Those ASETs are pretty distinctive.

 

[sleeprequired]

lol... yes they are aren't they... i reported the post and asked for it to be removed...

 

[Christina...]

yeah, once you've been here for a couple months it's easy to tell which vendor a person is working with. I wasn't sure if John could answer either, thats why I posted, but you had asked for Vendor opinions only so I wanted to point out that I was not an expert like John.

I know that you already realize that you have a beautiful diamond, but FWIW, I think that this stone will have an amazing combination of fire and scintillation. I assume that you were referring to Jonathons article about the effects of minor facets on a diamonds performance in the above post?

 

[sleeprequired]

Wow was that article actually written by John? Well there you go. Yeah I was getting at how the stars and LGF effect fire and scintillation, but more specifically how the star and LGF number on the reports is secondary to the actual IS and ASET image. Trying to work it out is all.

 

[Christina...]

The one that I was referring to was written by Jonathon at GOG. I'll see if I can find it and link it for you. John Pollard has written many articles too, I'm not sure if one specifically on the effect on lgfs and star angles, but it's quite possible.

http://www.goodoldgold.com/content.php?c=98

if this isn't the one that you read, then you will find this one interesting and informative as well.

 

[John P]

Everyone here is generous in their acknowledgments and I'd like to hand the compliments right back. The collection of regulars helping you here has a strong body of knowledge and experience.

The forum policies typically permit input as long as the pro is providing education or clarification and doesn't take a for-or-against position for any given stone. If I'm wrong the admin is free to remove my comments.

Sleeprequired: You're asking some extremely minute questions, which I personally love to discuss (!), but it's important to keep things in-context.

Starting at square one: A diamond's overall caliber of performance is largely determined when it's sawed and blocked. This is when table size and main angles are established. Blocking and cross-working also determine much with regard to the overall level of cut precision and consistency in the main facets. Brillianteering follows. In diamonds of high cut caliber this stage involves "clean-up" of things that might have strayed in blocking and cross-working. It's also when the break facets and stars are fine-tuned. Of those final facets the lower halves (arguably) have the most potential for optical influence, especially in diamonds outside of the near-Tolkowsky envelope. There is also the possibility for manipulation of the breaks beyond a standardized degree which can result in a stone that is painted or dug-out. Last come the stars. Of these elements the stars, by themselves, have the least overall optical influence.

So in diamonds with established top performance and cut-precision the details you're deliberating are tiny elements of an overall fireworks show. They are like finishing notes in a universally lauded wine...do you like an ethereal hint of dark cherry at the end...or do you prefer a single note of blackberry? Do you know? Practically, I believe such comparisons are only possible in real life. And many people won't even mark the differences without study or experience.

With regard to your comparisons, there is also the matter of photography standardization. In general we can make macro interpretations - overall light return, amount of leakage, contrast, etc. - between reflectors (IS, ASET, H&A) even if setups vary slightly. But you're digging down to a different level. The relative appearance of contrast leakage (white triangles) relative to obstruction (pairs of black triangles) associated with the star facets can photograph differently from photo setup to setup based on the strength of backlighting under the Ideal-Scope and girdle height as it relates to angular delineations in the ASET cone. Put simply, diamonds with notably different star lengths (let's presume perfectly consistent cutting) can resemble each other in two different setups. So detailed research and conclusions are great within informative articles. But it is impractical to apply X setup's micro-checklist to (strict) interpretations of photos taken in Y or Z setups.

i think it's very close in terms of the spots that are showing the fire and scintillation under the heading 'lightview #1 with diamond'. Hope i'm making sense...

If 'lightview #1' is attributable to Gemex, Isee or Imagem be aware that certain diamonds will "max out" the programmed metric in one machine or the next. That's not good or bad, it just "is." But just because a certain diamond "pops" in one metric doesn't mean that it will max out differently designed metrics - or your own eye. With that said I find the information all of these machines provide interesting (and different) taken in-context.

i also noticed in the ASET image some of the arrow are blue instead of black... any other comments appreciated.

No problem there. The black is the reflection of the camera lens from the highest angle directly above. The blue is part of the ASET cone which begins at 75 degrees and proceeds up until the camera lens "takes over."

You have clearly done detailed research and read good, informative articles. But going back to the tasting room comparison...you have obviously learned how to select choice cuts of USDA Prime. Now only real life sensory perception can draw you to the exact seasoning you prefer. For me the details you're chasing are as minute, perceptually, as the difference between a dash - or a sprinkle - of salt & pepper over your searing, sizzling ribeye on the grill.

Is it lunchtime yet?

 

[Gypsy]

John, have I mentioned that I love you?

 

[sleeprequired]

I emailed forum admin and they don't have a problem providing people are asking general questions regarding performance and using examples to speak about differences in performance. From the examples above I think i've worked out that overall performance would be generally excellent, with the slightest slant towards scintillation/fire vs pure light return, and that the IS shows that there should be some good flashes (as per GOG article on minor facets) of fire and good scintillation and plenty of contrast etc etc.

One video i really did like was the one with the eighternity diamond and the solasfera. If i was buying for myself i would probably look at the eighternity to be honest. Do those diamonds give up or sacrifice anything to obtain such great fire/scintillation?

and just for the record, does it help you if i like Wagyu, hence wanting to know so much more and just having to have a special stone within a special category and I think that's only going to happen by pure luck or with a lot of input from all the 'sperts'

 

[Gypsy]

Oh yes. They do give up. Those extra facet diamonds are busy busy busy. All that rapid fire flash. IMO they look best in larger sizes (1.5 plus) but again, it's a preference thing.

 

[sleeprequired]

right so there's that personal preference coming in because personally from someone whose looked at very few diamonds I like that fact that there's not an obvious arrows pattern in plain view looking at the diamond, whereas someone looking for a pattern will see a very busy diamond because the pattern is so intricate. I find all the pinpoint flashes & scintillation to be very appealing and the diamond just seems more alive..... to me...

 

[Gypsy]

I don't really like either for myself, that's why I don't own one over 7 points. One is too busy for me the other is too cookie cutter. In rounds the only faceting I like is OECs and earlier Transitionals and those only in true antique/vintage stones the ideal performance round old cuts are too cookie cutter for me too. That's pretty much it. I used to own this one: [URL='https://www.pricescope.com/community/threads/dreamers-new-to-me-aurora-band.166650/']https://www.pricescope.com/community/threads/dreamers-new-to-me-aurora-band.166650/[/URL] But the thirty two pointers were even too much for me. I like personality and in my diamonds I generally prefer old cuts (rounds and marquise) or fancies (cushions, pears, ovals, asschers, emerald cuts...).

 

[sleeprequired]

wow that's a really nice ring...

so you're a fan of broadflash as opposed to poinpoint then? would that be an accurate statement. I do like the broadflash too, but i think if i had to choose between one extreme (eighternity) or the other (OEC) it would be the poinpoint i would go for first... to be honest to me it's either the eighternity or the OEC... so there you go, H&A is my personal last preference..

 

[Gypsy]

It's a gorgeous ring. I actually used to get mesmerized driving with it on from the fire it throws. It got a ton of attention whenever I wore it too. It's amazing and BGD executed it exactly as I wanted (that's their CAD work). It's got the perfect home for it now with Dreamer (who can actually take great pics of it. My pics were just sad). I miss it sometimes. I might have another made someday, but with smaller stones.

 

[sleeprequired]

so you're saying you don't like big diamonds in general? Is that what the over 7 points comment was? (sorry my diamond lingo is still limited ) It doesn't surprise me that i like one extreme or the other, that's me all over. Having said that, I think a H & A will be perfect for her because she's right in the middle (and it's the only brand she knows as well) in terms of personality, very balanced.

 

[John P]

John, have I mentioned that I love you?

Très sweet of you to say, mon amie ~ and it's a two-way street.

and just for the record, does it help you if i like Wagyu, hence wanting to know so much more and just having to have a special stone within a special category and I think that's only going to happen by pure luck or with a lot of input from all the 'sperts'

Understood completely. I'm a dedicated foodie. I think my FB albums have more photos of food than folks in them, so I get you. In fact when I started my own diamond search prior to being in the business I took a similar approach and it was e-discussions like this which really crystallized (pun intended) concepts for me. When I ultimately made live comparisons, head-to-head, having such discussions prepared me to see how visible (or not) the concepts and correlations I'd made were IRL.

You're at that stage now. By all means continue the discussion but your eyes will have to decide - for you and for her. And while videos are helpful there's no substitute for live performance of a diamond seen in actual scale with binocular vision in live, 3D depth.

FWIW I agree completely with Gypsy about proprietary extra faceted cuts. They're smashing in larger sizes, but lose effectiveness when smaller. It's a logical result of surface area per facet and resultant virtual facets. As a comparison, think of a disco ball with normal sized mirrors flashing next to one with twice as many mirrors. The one with smaller mirrors will have a different character; more rapid, smaller flashes. Under the lights it will really sizzle, but the flashes won't be as large or intense as those from the normal ball. And if you start shrinking both of them down the one with more mirrors will lose effectiveness before the normal one. Alternately if you make them bigger and bigger the one with more mirrors will continue to be active while the normal one begins to slow in its character.

 

[Gypsy]

so you're saying you don't like big diamonds in general? Is that what the over 7 points comment was? (sorry my diamond lingo is still limited ) It doesn't surprise me that i like one extreme or the other, that's me all over. Having said that, I think a H & A will be perfect for her because she's right in the middle (and it's the only brand she knows as well) in terms of personality, very balanced.

OMG. No. I LOVE big diamonds, and yes it is a curse. I just don't really care for large round brilliants FOR MYSELF. I always think they look lovely on others but for me, I find them kinda boring in larger sizes. For larger diamonds I prefer other cuts. That's all. I'm just not a round brilliant girl. Or an extra facet round girl (although I did see one at 2 carats that was pretty cool). That's doesn't mean I don't appreciate them. But... to use your food analogy. RB are like chicken to me. I have had some expertly prepared chicken (my DH actually makes a chicken dish that is to die for), and really love it when it's done well. But if you asked me what my favorite foods are to eat I don't think "chicken" would rank even in the top ten-- there is just so much more out there that I prefer to even expertly prepared chicken. That doesn't mean I don't love a good chicken dish. It just means I'm not likely to go out of my way or spend a lot of money to order one because there will almost always be something else on the menu I like more.

John ((HUGS))

 

[Christina...]

I love these food analogies! So often around here we make the car analogies and they get old, it's nice to spice (pun intended ) things up.

Sleeprequired: I understand what your saying about extremes. I prefer one end the spectrum or the other, and in between is just sort of ho hum for me. I suppose I've always been that way, so it makes sense that it carries over into jewelry preferences. It's not that I want to stand out, it's more that I don't want to blend in kwim?! I agree with the others that now that you know what to look for in a super cut, you will have to look at many many in person to determine which flavor you prefer. I just purchased my first RB and knew that I wanted a teeny table and high crown (I love to look at it from the side and the bezels look so big and chunky) and loads of fire. But like you it took lots of research to realize what look I wanted and what to look for specifically in it cut to attain that. I think it's like the girl your buying this for, you knew her when you saw her.

 

[sleeprequired]

lol, at the moment i'm a cereal man while it's prime steak time for you guys...

here's a question, why do most ideal scopes have black arrows and show red light return, while others look like this? i'm thinking this image below is the arrows view in the H & A viewer? it seems the arrows view has a darker 'middle ring' (arround the arrow shafts' while the IS ones with the red/pink and balck arrows tend not to... comments?

 

[Gypsy]

I'm pretty sure that's not an idealscope image.

 

[sleeprequired]

Thanks Gypsy... it's usually paired with the hearts view in a hearts and arrows tutorial but I don't think it's the true Ideal Scope either...