Hit me if you can!

[Stephan]

I know this topic can become an argue, but let''s play!

On this forum, you have a lot of links to honnest diamond dealers, who sells quality.

Whiteflash is one of them, with the "A Cut Above" diamond.
You can see the pics of these beautiful diamonds, and the Sarin''s too; and we can say that these stones seem to be cut with a great precision.

ACA lovers don''t hate me, but it''s very difficult to find ACA''s with crown and pavilion angles in the "sweet" zone.
The combination is often a little "extreme" (34.9-40.9 etc...)
The most of them have only 2 EX on the HCA (don''t misunderstand me, it''s still very good).

So what''s the secret?

 

[mdx]

Hi Stephen

Why do you say.

"The combination is often a little "extreme" (34.9-40.9 etc...) Looks pretty good to me

and what do you interpret as "the sweet zone" and why.

Johan

 

[Stephan]

Hi Johan!

When I talk about the sweet zone, I mean that with a 34.9 crown, I prefer a shallower pavilion (for ex: 40.6) and with a 40.9 pavilion, I prefer a shallower crown (for ex: 33.7).

 

[mdx]

Ok I see where you are coming from.
Lets see what this thread develops
Johan

 

[jqwest]

My ACA has a 34.8 crown and a 40.8 pavillion. Sweet zone or not?

 

[Garry H (Cut Nut)]

I would like to see more cutters producing diamonds with radically different crown and pavilion angle combinations so they can maximise yeild from different types of rough and still produce beautiful diamonds.

The difference between the yields on the proportions you quoted Stephan are around 2.5% from typical larger portions of sawn octahedra.

Given that ACA produce very symmetrical stones with nice girdle thickness it makes commercial sense to ensure those stones are cut to the upper boundaries of excellent proportions. If as you say many stones are near that boundary, then surely that is a testament to great skill?

 

[elmo]

It is the same with superbcert last time I checked, lots of stones with 40.9-41.0 degree pavilions.

The diamonds still look good, people still buy them, and the bottom line looks a little better at the end of the year.

 

[aljdewey]

Can only chime in with my ACA proportions here......34.6 crown, 40.7 pavilion, and it scores all ex.




All I can tell you is what I see.......flashes of white light and rainbow colors that make the stone look ALIVE. It's like a dazzling light show.




I've had more people......strangers, too!........stop in the mall etc. and ask to get a closer look at it, and they comment on how they've never seen a ring sparkle like that. Very cool.

 

[Mara]

This brings up again the whole 'what is the real visual difference between a 40.9 and 41 pav angle'. I think Brian at WhiteFlash noted that at the 41 pav angle point you may start to lose some of the great H&A symmetry if it is indeed a H&A stone. But visually? I don't know if there'd be a difference to naked eye.




My two cents on the whole issue? WhiteFlash cuts with precision to yield a beautiful stone. We all know there are great combinations of pav and crown angles that make a stone beautiful, then there is also the small sweet spot that is typically touted (different from Stephans' sweet spot criteria!). I think that is why it's so great that each vendor has tons of combinations, something for everyone. If I wanted more of a FIC...I'd look for a small table and a larger crown angle. Something that is still doable even with an ACA or a SC stone....but if I wanted to be REALLY picky and get the typical sweet spot stone..e.g. 40.8 pav angle and 34.8 crown angle which I think is what my fiance's new ACA is....then I have that option too. I quite like that many of the vendors carry different options, not just the same cookie cutter stone over and over. That'd be no fun!

If I am going to search out a stone and have different options, I am going to hold out for what is most important to me. In today's day and age with flexibility of internet, there's no reason to really compromise on whatever people feel are important to them.

 

[Stephan]

I think that a brand like "Venus by Infinity Diamonds" does not cut for the yeld and takes consideration of the MSU charts.
You can look at the proportions of some Infinity Diamonds by clicking on this link.
I decided to buy an Infinity Diamond and I can't wait to post some pics when my stone is cut!
Still waiting, Paul!

 

[Rhino]

I don't think Stephan is referring to just pavilion angles but the the crown/pavilion combo. He may (and rightfully so) consider crown angles 34 - 34.5 with pavilion angles 40.7-40.9 to be sweeter? I'd personally add other dimensions to this regarding the minor facets but insofar as Sarin's go that's a nice start. Congrats on your decision Stephan.

 

[Stephan]

Yes, Rhino, You got it!

I like the stones you sell too, they have an average combo of 34.2-40.8.
That't much better than the typical ACA 34.8-40.9

 

[pqcollectibles]

Just curious here, but...... Have you seen diamonds cut to the crown/pavillion angles combos you've mentioned side by side, comparing performance live and in person??

Many experts here have often said that any number of crown/pavillion angles combinations will produce beautifully performing diamonds. Just because you happen to prefer a particular combination does not make another combination a bad choice for other people.

BTW,.... Most ACA's score Ex/Ex/Ex/VG on the HCA. And, WF has recently listed several diamonds that score Ex/Ex/Ex/Ex on the HCA as well.

 

[niceice]

We do believe that Stephen is referring to what is commonly referred to as "Super Ideal" as the Sweet Spot? The center region of the range for ideal cut...

There is degredation of the H&A pattern past the 40.9 degree mark... However 40.9 degrees was actually the target for H&A production in the mid-1990's when TRUE H&A's were available. Likewise, the arrows pattern is often distorted outside the range of 34.3 - 34.8 degrees.

 

[pqcollectibles]

Thanks, R/T! I got the upshot of the "sweet spot" combo. I was curious why Stephan preferred a particular angle combo. A quick search of Stephan's past PS posts led me to the answer of that question.

According to Stephan's posts, Stephan already has several TIC's. Stephan has seen BIC's and doesn't care for them. Stephan wants a FIC diamond and is working with Paul Antwerp to custom cut one. Hence the particular angle combination. Which, I guess

was recommended by Paul Antwerp.

 

[aljdewey]

Actually, I'm not sure that's entirely the heart of the issue, PQ.




What I understand Stephan to be noting is that the angles are often at the upper end of the range on BOTH angles, and he's asking about how that affects the performance.




The crown/pav angles are almost like a yin-yang.....for each move up in one angle, there should be a corresponding move down in the other angle to preserve "optimal" performance.




So, if the "superideal" range on crown is 34.3 to 34.8, and the range on pavilion angle is 40.6 to 40.9....Stephan is observing that many of the stones reflect angles on the upper end of BOTH ranges, instead of upper/lower. So,


he's saying "34.3 would be most optimally suited for 40.9, yet most of these stones are closer to the 34.8 than the 34.3."




I guess my comment would be this. If the ranges were bigger, I'd expect it to have a much more direct impact on performance. When you're talking about SUCH a narrow window of ranges, I'm not sure I think there'd be a hugely perceptible difference.

 

[pqcollectibles]

----------------
On 1/19/2004 2:08:18 AM Stephan wrote:

I think that a brand like 'Venus by Infinity Diamonds' does not cut for the yeld and takes consideration of the MSU charts.
You can look at the proportions of some Infinity Diamonds by clicking on this link.
I decided to buy an Infinity Diamond and I can't wait to post some pics when my stone is cut!
Still waiting, Paul!

----------------

The MSU studies are highly regarded in the diamond industry for their insight into optics and performance. Garry Holloway has consulted extensively in projects and co-authored reports.

Venus diamonds are offered in a variety of angle combinations. I visited the link an interesting Venus .71 carat, H, VS1? Here are the stats.

0.7 TIC, Ex/Ex/Ex/Ex on the HCA, but definitely not the "sweet spot" in angle combo Stephan was talking.

From researching Stephan's posts, I see that he has an arrangement with Paul Antwerp to custom cut a diamond for him. I am guessing

they have discussed the appropriate angle combo that would yield the BIC Stephan is looking for.

The whole cutting issue is not as straight forward as Stephan indicates in his post. Paul Antwerp has been so gracious on many occassions to grace the Forum with his knowledge and insight into the world of diamond cutting. I also know from conversations with Brian Gavin, diamond rough has a personality of it's own. Rough doesn't necessarily lend itself to be cut one particular way or another. While Stephan thinks a given "Super Ideal" diamond was cut at the upper limit to retain weight, it may have been a case of working with the rough to maximize the performance of the diamond produced. It will be interesting to see the results when Stephan's diamond is complete.

 

[Rhino]

Hi PQ, Al,




PQ you are correct. Rough can seem to have a mind of it's own regarding cutting and I've personally seen stones of the 34.8/40.9 that have had superior optics to 34.3/40.8 combos but it really depends on where it's coming from and the craftsmanship of the diamond in question.




However, when given the choice and all I had were the blind numbers to go on I would prefer a 34.3/40.7-8 combo over a 34.8/40.9-41 anyday (considering most other factors are equal).




It really depends on the diamond in question and I say let each one stand or fall on it's own merits. 4 Ex's on the HCA while sounding nice doesn't impress me either. Many stones I've seen/tested have had less than desireable optics ... especially with the Venus stone PQ posted a link to with 40.4 pavilion angles.




I'd be interested to see the stone you're talking about Stephan as I've had the opportunity to personally see stones from Paul in the past and have tested a few.

 

[ringbling17]

My ACA is 34.3/40.8 on the AGS and 34.1/40.8 on the Sarin.
When D. Atlas ran it on their machine, they got 34.3/40.8.
Is there really a visual difference?

Will someone really come up to you and after examining your diamond say, " I suspect that your crown angle and pavilion angle is not in the sweet spot"?

All everyone will notice is how blindingly beautiful your diamond is.

 

[aljdewey]

----------------
On 1/20/2004 2:08:07 PM niceice wrote:





There is degredation of the H&A pattern past the 40.9 degree mark... However 40.9 degrees was actually the target for H&A production in the mid-1990's when TRUE H&A's were available. Likewise, the arrows pattern is often distorted outside the range of 34.3 - 34.8 degrees.
----------------

So, I guess what Stephan is saying is that he prefers the 34.2/40.8 combo.......even though it distorts the arrows pattern. To each his own.....he's entitled to his preference, even though it wouldn't be mine.

I think that debating over who's stones are *more* beautiful is kinda pointless, to be honest. We are talking about stones that have amazing light return and outshine most of the common junk available on the retail market. Let's keep in mind, too, that the HCA is limited in what it takes into account. It doesn't penalize a stone that has a less crisp H&A pattern. It doesn't penalize a stone that isn't polished as finely as others. It doesn't take into account workmanship and many other things.

Is it really necessary to nitpick whose is *subjectively* better/more beautiful/more desirable/WHATEVER?

WF makes BEAUTIFUL ACA stones. I've NEVER read a negative review on a single ACA stone. Jonathan picks BEAUTIFUL stones. Similarly, I've NVER read a negative review on the quality of the stones he picks.

I guess I'm not sure what the point is Stephan? What was it again?

 

[aljdewey]

Actually, stephan, I DID take a look. My goal isn't to knock the Venus stone, but you're suggesting that they hold to some "loftier" standard, let's take a look. I see one of the Venus stones on a site, and I note the following:




1. A 40.4 pav. angle is NOT in the sweet spot......the most favorable pav angles are widely considered to be between 40.6 and 40.9.




2. Sorry, but I thinkk that a stone that gets VG instead of EX or ID on polish shouldn't be in the same league with "ideal" stones anyway.

 

[mdx]

PQ I tend to agree with you on your observations.

Sometimes I think in our search for perfection we display acute tunnel vision with the notions of “sweet spots” and perceived “super ideal cuts”. The strange love of Hearts and Arrows which is really just a display of symmetry doesn’t help much either.

I believe there is a much broader range of pav/cr and table combinations that produce spectacular stones sometimes far more beautiful than what we are calling “super ideal”

Here is an actual example.

We recently where lucky enough to acquire a large (8+ct) rough diamond of exceptional color (D) and clarity (VVS2) with strong blue fluorescence. Unfortunately the diamond was an irregular shape(cleavage) with some graining forcing the cutting into a shallow pavilion angle. After much pondering and sleepless nights and a lot of help from Diamcalc the cutter came up with a set of dimensions that would seem bizarre to the promoters of the “sweet spot”

The end result was one of the liveliest and beautiful diamonds I have ever seen.

Indecently this diamond sold to the first person we showed it to. Maybe that was just a coincidence,

The numbers are.
Weight =3.57 ct
Recovery = 44.8% (not that good but ok for the shape)
Color = D
Clarity = VVS2
Total Height = 59.7%
Table = 57%
Crown Angle = 37 degrees (16.2%)
Pavilion Angle= 39.9 degrees (41.8%)
Girdle = Med – slightly thick
Culet = Very Small

Some food for thought

Johan

 

[pqcollectibles]

Eeewwww!! MDX!! That diamond sounds really kewl!!

I would have loved to have seen it!! Bet it looked much larger than the traditional carat weight/diameter would normally be. Had I been in that person's shoes, I might have snatched it away from you too!!

True works of art grab your eye, burn themselves into your brain, and take speak to your soul.

Every great artist loves a challenge and it sounds like you rose to the occassion!!

It's easy to view any range of angle combinations and find them appealing, even spectacular. The trick is achieving the combinations that create show stopping performers. To work with the personality of the rough, as you so aptly pointed out, MDX, is not always easy or straight forward.

 

[Mara]

Wow MDX....with those angles it would seem the diamond would be quite fiery...was this the case?




Interesting that you mention DiamCalc as being the assistant to figuring out how to best cut the rough. Excellent idea!

Did you take a Scope image for light return? Would be great to see.

 

[mdx]

Yes Mara the diamond was very fiery; the strong fluorescence also added an interesting flash of color in outdoor light. In terms of an Idealscope image I still have the Sarin file that I can import into Diamcalc when I get to the office to-morrow morning. In the meantime I have punched in the numbers manually. Here is the generated image. Note the good contrast.

Johan

 

[fire&ice]

----------------
On 1/20/2004 11:21:38 PM pqcollectibles wrote:

True works of art grab your eye, burn themselves into your brain, and take speak to your soul.

Every great artist loves a challenge and it sounds like you rose to the occassion!!

It's easy to view any range of angle combinations and find them appealing, even spectacular. The trick is achieving the combinations that create show stopping performers. To work with the personality of the rough, as you so aptly pointed out, MDX, is not always easy or straight forward.

----------------

You have expressed what I beat the dead horse to express. On this board, we seem to really lose sight of this. Diamonds are like people & art - many different facets determine beauty (especially in the eyes of the beholder). Though, the human eye is drawn towards symmetry as perceived beauty - but not necessarily perfect symmetry & some are more sensitive to this than others.

So, I have no specific scientific anything to add. It's me - but I still hold a diamond to some romantic notion than reducing it to "numbers" on a piece of paper.

 

[Mara]

----------------
On 1/21/2004 9:53:57 AM fire&ice wrote:





I still hold a diamond to some romantic notion than reducing it to 'numbers' on a piece of paper.

----------------

I can definitely see that point...but I'm a numbers girl. I play with numbers in my head all the time. I actually like quantifying a diamond on paper, breaking it down, seeing the images that show light return, how the diamond will perform in various lights, pictures of the diamond, inclusions, etc. Of course it doesn't mean that the diamond will knock my socks off in person...but I have yet to see a person here on Pscope who did all that research, got some amazing stone in terms of numbers, reports, images etc and was disappointed. Doesn't mean there aren't plenty of other amazing stones out there, e.g. my shallow cut BIC which I love...but in terms of future buying, for me, I love having the numbers to play around with.

For example with Greg's ACA stone. That stone literally could not have been anything more for me to love it. The numbers are all excellent, the IS image is off the chart...the picture of the stone looks flawless (!). It's practically perfect in terms of meeting stringent requirements. Chances are 99.999999% that when I get it...I will just faint. The other .000001% may be that I think...hmm this thing looks weird. But am I worried at all about that small chance I won't love it? Nope. Because that thing performed so well in every way so far that I am sure my eyes will corroborate what the numbers said. I could have settled for another ACA...one with more extreme angles and maybe a different look, but I specifically set out to find a stone that was smack dab in the middle of that touted 'sweet spot' with great information...because I really wanted to see what it looked like in person!

I guess for me...I am not going to SET OUT to find a BIC or a FIC...but rather one that has the best blend of both worlds, and hit that 'sweet spot' that I did hit with Greg's stone..with the crown and pav angles widely accepted by the industry. But if I come across a BIC or FIC in person...sure I would give it some consideration. Obviously we did without even knowing it in the form of my lovely e-ring stone. Online? Probably not...not when there are other stones that I can easily search out that have the 99.999999% chance of being beautiful, whereas an online BIC or FIC may have something more like a 80% chance in person...because I firmly believe those types of more extreme stones ARE meant to be judged by eyes.

In terms of online purchases, which is more safe? I would venture to say the one that looks excellent by all numbers AND pictures rather than one that has so-so numbers and okay pictures.

I bet if you polled 100 people in Times Square, more people would find a BIC or FIC with extreme angles less attractive than a 'sweet spot' 'superideal' (using all the terminology together..oooh)....but thats just my two cents.

And HAH you can't ban me!

 

[fire&ice]

----------------
On 1/21/2004 12:53:56 PM Mara wrote:

----------------
.but I'm a numbers girl. I play with numbers in my head all the time. I actually like quantifying a diamond on paper, breaking it down, seeing the images that show light return, how the diamond will perform in various lights, pictures of the diamond, inclusions, etc.

And HAH you can't ban me!

----------------

That's just it. I'm not a numbers girl. I really fly by the seat of my pants when my "better" half has to put *everything* in a spread sheet. Drives me crazy. Drives him crazy that 99% of the time I just go w/ my gut. I think I am analyizing data in my head though. Funny, we often come to the very same conclusion - just *completely* different methods of drawing the conclusion.

Can't really comment about the Times Square bet. But, I'd probably like each for different reasons. I'd pick them all.

Yeah, Leonid took away that function which might be very valuable when someone gets too pesky.

But I knew the power - if only for a moment!

Thing is, at the end of the day, most well cut diamonds are gonna look pretty darn good regardless.

 

[diamondlil]

----------------
On 1/21/2004 1:47:10 PM fire&ice wrote:

That's just it. I'm not a numbers girl. I really fly by the seat of my pants when my 'better' half has to put *everything* in a spread sheet. Drives me crazy. Drives him crazy that 99% of the time I just go w/ my gut. I think I am analyizing data in my head though. Funny, we often come to the very same conclusion - just *completely* different methods of drawing the conclusion.


----------------

LMAO, F&I. My DH and I work things out the same way.

Diamondlil

 

[Garry H (Cut Nut)]

Here are a couple of examples of interesting proportions that will get great yields from sawn tops (BIC) or roundish maekable (FIC) roughs.