Cut Rules OUT OF DATE!!!

[biscuit]

Hi again!

BEFORE you blindly consider buying an H&A rock or an AGS000 PLEASE READ this!

I have been checking out the web resources EXTENSIVELY on diamonds, and started poking around locally. I didn't want to go to a jeweler, so the first place I started looking was with registered gemmologists. What seems to be happening consistently is that the current standards of cut quality are being called into question, and EVEN LOCAL gemmologists know this!

Basically, the Tolkowski cut/American Ideal has kept the cutters within a box for the past 80 years, but new technology is showing that maximum light return/fire return paired with minimum leakage is found with crown angles that you can't even find on the market today! Today, crown angles are cut around 30 degrees...in time, we may see diamonds cut with crown angles as low as 15 degrees!!!!

One gemmologist I spoke with, who's been in the trade for over 40 years (initially as a goldsmith, now as a gemmologist), went to a conference with the famous Tolkowski's grandson. Apparently it's a family business. This Tolkowski would put two slides of two diamonds up on the overhead sceen, and ask the room full of experts which rock looked more brilliant. As you probably guessed, all the experts would pick a rock who's cut was WAY outside AGS stardards (even greater than an AGS10!) without knowing it, and then Tolwoswki would have the joy of telling them all that they picked a rock with a crown angle of 15 degrees OVER an AGS 000 IDEAL CUT ROCK! He made a room full of the world's gem experts look like idiots!

Well, after talking to this gentleman, I felt somewhat confused because he basically contradicted EVERYTHING that *most* diamond dealers online are saying. Granted, there are quite a few honest gemmologists who will post the truth out here on pricescope, but their voice isn't that loud (would you want to upset an industry that makes it's money through close connections?). Usually they post pretty ambiguously so as not to rock the boat. So I did a little more online searching.

And I found some info out here that confirmed what he was saying. If you go to the diamond calc section of Pricescope, there is a link to some VERY recent studies being done in Russia (There are ways of finding a fuller representation of the report elsewhere online). Basically, the charts confirmend EXACTLY what the local gemmologist told me - that it is quite possible to have a rock with an "UNCHARTED" (by current standards) crown angle and have a MORE BEAUTIFUL diamond than and AGS 000 IDEAL!!! Not only that, but the amount of variance *within* current cut grades is quite significant...meaning that not every AGS0 looks like every other one...in fact there are AGS2's that return more light/fire!

ANY seasoned gemmologist will tell you this...that for whatever reason, consumers will sometimes consistently pick non-ideal rocks OVER ideal rocks in a side by side sight comparison. This Russian study offers a solid explanation why this might occur.

WHAT DOES ALL OF THIS MEAN???

We, the consumer, probably won't see these new rocks for quite some time. But please be aware that this information is powerful for us to be armed with. ANY salesperson claiming that their diamond is the most beautiful cut for light return resons is FULL OF IT. Don't swallow their sales pitch hook, line and sinker!

IF you're in the market for a diamond, DON'T swallow everything you hear, even in a forum like this. And when reading sites that sell diamonds, be even more careful. Use your head...many of these people are sales people...people that post in these forums. There are LOTS of beautiful diamonds out there, but there are lots of diamonds that cost WAY MORE than they should relative to the market. The internet is a GREAT way to save money, but there is NOTHING that compares to a side by side eye comparison. The fact that Sarin angles vary from machine to machine is FURTHER EVIDENCE that all info out here isn't quite as reliable as the human eye. SO, BE CAREFUL, GET EDUCATED, and I guess HAVE FUN!

"KNOWLEDGE IS POWER"

thanks again all!

 

[pricescope]

Cool post Biscuit.

It is known that light return can be higher when the crown is shallower. However, human perception of the light return (or brightness) is not the same as brilliance which involves also dynamic contrast of the diamond.

A stone can be very bright but have less contrast and fire and thus be not as pleasant as maybe darker but lively one.

Some people prefer diamonds with more fire than brightness hence it is also a matter of a balance in one stone.

Different people can prefer different looking diamonds based on their traditions, age, gender, etc.....

That is why better to look with your own eyes at different stones and decide for yourself

Have you been able to see and compare different cut stones yourself? I just would love to hear what you would like.

Keep us posted.

 

[biscuit]

Hi Leonid!

Thank you for consistently posting good info out here...I really appreciate what you've made available!

As you can probably tell from some of my recent posts, I tend to be a bit of a numbers head...and some that are close to me might call me a bit of a perfectionist. HOPEFULLY all of my rablings out here reflect something of my desire to get the most beautiful rock for my most beautiful girl.

As of yet, I've had a bit of difficulty bridging the gap between what I've learned out here on the net and actually observing it it stores...primarily because the few B&M's that I've been to don't have Sarin reports readily available. I did do some digging and found out that there are two Sarin-type machines in my city, but they aren't available to the public (they're owned by cutters).

Being on the west coast of Canada, there are a lot of Canadian cut rocks from the mine up north...and I've seen a few of their Polar Bear branded rocks that are *absolutely* gorgeous. They carry a hefty price tag though, and the taxes up here are QUITE significant. On a .55ct rock, were talking about a difference of $800US AVERAGE between pseudo-wholsale local gemmologists and the net. Sick, right? I've seen other rocks I've liked, but without more info it's hard to know what I'm looking at.

In looking at the stones, I've noticed a few personal preferences....
After reading all the info on the net, I was pretty stuck on VS1 clarity, but I've realized that there are a significant number of SI1's out there that are *truly* eye clean. I'd probably feel most comfortable with buying a VS2 on the net. I also wasn't as set on color as I should be, but I'm now shooting for an F...the difference seems more observable than clarity grades.

As far as different cut stones, i've been running into walls...that really is the next step in my search process. I need to find someone in my city that can accurately represent different cut qualities (and cut types) so that in some way I'll be able to consider purchasing on the net. As of right now I feel a little safer buying locally, but I hope I can see what I need to that will give me the confidence to buy online.

I'm beginning to understand why so many gemmologists out here *really* suggest getting out and seeing as many rocks as possible - it might be some of the best advice available. From my limited experience, it seems like you are speaking great wisdom when talking about the importance of individual preference. Leonid, thanks for all your help - I'll keep you up to date on my diamond observing experience.

Thanks again!

 

[Derek]

Biscut-
Based on my experiance over the last number of months of looking at stones, you are going to find that those jewelers who care enough to carry the very best won't have too many (if any) 'bad' examples to compare to. That made it really tough for me when I first started looking. I'm getting pretty consistent now though in that I'm able to choose 'better' cut stones when comparing them next to each other. Today I looked at 5 different stones and without knowing anything about them I always choose the most expensive (jewelers aren't dumb, you get charged for beauty). The thing that really threw me though was my favorite stone scored an HCA 3.3!!! I'm very suspicious that the measurements I was given were not correct as they did not come off a sarin report like the rest of the stones which scored lower, they were off what I would consider a marketing report from the manufacturer.
I agree with you 100% nothing is as reliable as the human eye, beauty is in the eye of the beholder.
Knowledge is power, experience is the key.
Good luck on your search!
-D

 

[biscuit]

Hi Derek!

Thanks for you thoughts! Quick question:

Are you finding that the stones that look the most beautiful to you, and as you say are better cut, are agreeing with what the resources on the web would call a better cut? I realize you had a weird experience today with the HCA of 3.3, but in general are the rocks you're choosing by eye turning out to be an HCA of 2 or less? Are their measurements ending up AGS 0/AGA 1A?

Thanks a ton!

 

[fire&ice]

I am convinced that your eye is the major determining factor to one's preceived diamonds beauty. I have seen stones w/ handsome pedigrees that didn't have the appeal to me that the stone I ended up with had. I was offered a represented "ideal cut" stone. It didn't sing to me. Neither did the price tag - at exactly $8,750 MORE THAN the cost of my stone (same specs except VVS1 vs SI1).

To continue the discussion over here Leonid, why does HCA penalize a table over 58%. Is that just an arbitrary cut-off? What about tables that may be closer to 58% than 60%?

My other question, when I plugged in my crown & pav. % (which may or may not be accurate) my stone received a score of 2.4. As I stated in another thread - that did not come as a surprise to me as I did not buy nor pay for an ideal cut. However by adjusting the table by 1 degree the score came up 1.7. Question, how much would the human eye preceive between 2.4 & 1.7.....Or, for that matter say 3.2 & 2.4 & 1.5? Could my eye appreciate an 1.5 HCA priced at $8,750 more than a 2.4 HCA (8,750 less)? I am trying quantify cut & price.

I would assume that at some point (or score) the preception would be very noticable to most people. When does that happen? Thing is my OEC scored a 4.4 and it's a handsome stone.

 

[pricescope]

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To continue the discussion over here Leonid, why does HCA penalize a table over 58%. Is that just an arbitrary cut-off? What about tables that may be closer to 58% than 60%?
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[oldminer]

Biscuit and all:

Thanks for the refreshing reminder that nothing stays the same forever. Not even in physics. Knowledge of even the fixed laws of nature gradually become refined and change, too.

I one problem have with way you said in the first post however. "...Today, crown angles are cut around 30 degrees...in time, we may see diamonds cut with crown angles as low as 15 degrees!"

Crown angles on many diamonds have been cut close to 30 degrees for a lot longer than "today". In fact, a 30 degree or less crown angle may give the possibility of great light return if combined with the right other parameters, BUT durability of the stone becomes a factor at 30 degrees and less. The crystal structure of a diamond is such that this angle or less creates a weak edge (girdle) and makes chipping more likely to occur. For this reason alone, we may see few of the predicted brilliant cuts with way less than a 30 degree angle. A 33 to 36 degree angle gives a diamond, even one with a thin girdle, quite a bit of added durability from chipping. This MUST be considered for diamonds being placed in daily wear rings. Especially when these stones are going to be high quality and high cost stones.

There may be quite a lot of innovation in cutting ahead and I welcome it. We may see some diamonds that look truly superb and cut in ways we had not imagined possible. I think that for a great combination of durability and visual appeal, we may not surpass many what is considered very fine cutting today. Some may disagree with this, but there is no factual basis, not yet at least, to base a different opinion upon. Maybe I will someday even change my mind on this. It just isn't time for that decision.

Wishful thinking, a hope to sell the commercial cut stone that looks good, and confusing the issues are all things that can be done with hyping the yet untried and basically theoretical data that has been uncovered with light research. Consumers who want a fine diamond can buy one without fear with the help of the present cut grading strategies. There may come a time when there are more choices. I have no problem with more choices, but right now the other round diamonds without fine cut pedigrees are mostly not up to the total performance of the near Tolkowsky cut stones. There are some less than ideal cut diamonds that do perform very well which can be readily and inexpensively detected with an Ideal-Scope or predicted with the HCA, but there are far more diamonds of fine make out in the present market that hardly need theoretical proof that they look excellent.

B&M stores that can show various cuts of diamonds have a greater opportunity than Internet vendors to sell less than today's recognized "ideal cut" range of stone. That is just fine. People buying a diamond via the Internet generally want a no issues type of cut where they will love the look of the stone regardless of color or clarity.

 

[biscuit]

DAVE ATLAS!

YOU ROCK!!!

THANK you for that reply! It was awesome!

 

[Garry H (Cut Nut)]

B this is an excellent and thought provoking thread.
Dave beat me to the jump on the girdle chipping issue - but it is possible to cut thicker girdles on very shallow crown diamonds (although often this reduces the weight return from the type of rough that gives great yeilds in very shallow crown angle diamonds).

If this ideal-scope image comes out it shows an AGS 10 diamond that performs very well indeed.
HCA ranks it under 2, which would cause quite a stir if anyone could find one - they are very very rare - maily because as you rightly point out - the trade and cutters avoid "unusual proportions".


Blind adherence to Tolkowsky, combined with the desire to cut slightly deeper pavilion angles, could probabaly lead to an estimate of $100 Billion dollars of waste over the past severaal decades.

The interesting thing is that it has always been taught that knowledge or even estimates of proportions can tell an "expert" all about a diamonds cut. The Ideal-Scope makes a complete mockery of that belief. Experts all to often never really look at diamonds - they do expert magnified examinations - but forget to loo and se if it looks good.

 

[biscuit]

Garry!

THANKS for the encouragement and the great example of one of the "weird" rocks that falls outside of the parameters of typical cutting today.

Question: Do you know of any cutters in the world that are seriously experimenting with low crown angle/thick girdle cuts? Perhaps the cutters in Russia?

I'm not holding my breath or anything...especially with a tentative proposal date less than six months away! Just wondering...

Thanks again!

 

[Garry H (Cut Nut)]

GIA have some of these samples in their survey study I believe.

your Gemo jeweller actually seems to have got his story a bit mixed up - the images he saw on the screen would have been from a GIA presentation - not the grand Nephew of Tolkowsky - Gabi T - who is a great guy - but not a scientist.

BTW that stone has great scores for light return on a DiamCalc cut quality. But the contrast is not great because the stone is so 'bright'.

I am making a movie of it which would be imteresting. It looks quite firey.

 

[Derek]

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Are you finding that the stones that look the most beautiful to you, and as you say are better cut, are agreeing with what the resources on the web would call a better cut?
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B-
Yes, everything seems to be in agreement in terms of HCA/Ideal-Scope and beauty. I have only had one possible exception, the 3.3 in which I don't trust the angle measurements I was given because it looked really good under the ideal-scope (and on it's own). I saw one other that was a 3.x but it was bezel set in a pendant. The setting was completly masking what was probably a dull outer edge including a huge grade maker SI2 feather.

I can't say the same about the AGS system though as it depends on which of the parameters is/are causing the high score(s) (like polish). I have seen one 000 that I absolutely would not buy. Unfortunatly I didn't get the angles on that one to score it. The problem I had with that one is probably more personal though. At certain angles the entire stone dimmed and all I saw was the eight arrow pattern, otherwise it was nice.
Good luck!
-D

 

[Garry H (Cut Nut)]

no idea if anyone is experimenting with bright cuts

 

[RubyBleu]

You might want to start thinking about what a "bad" diamond looks like vs a good one. Go to your "People's" in Canada (Zales) and see those $3,999 CAN caraters.... note the look - then go down to Brinkhouse (in the hotel VAncouver) or a Ragnar's and see a "Polar Bear" (Sirius) Diamond - even go to your local Birks, or Spence Diamond's - check their stones - They all rock. You'll know quality when you see it.

Bad cuts look bad - good and great cuts look great - forget about the numbers after you start looking at the stone - Judge it on its merit.

RB