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OEC Ideal Cut?

ForteKitty

Ideal_Rock
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Oct 7, 2004
Messages
4,640
Yeah, I agree with with DS. You gotta use your eyes and throw those numbers out the window. And I say this as a consumer and risk taker who has purchased over 100 old cuts based on a few crappy pictures alone, most with no return policy, then sent maybe half of them to GIA... the numbers don't tell anything a good pair of eyes can't instantly see in a glance. I would NEVER tell someone "this is a good oec based on numbers", because it could possibly look like crap.

Also, I sold a 42% table graded OEC by GIA with perfect little flower petals, so those do exist and your assessment isn't accurate. Only three out of the four criteria need to be met, so the OEC designation doesn't require the lower half facet length to be 60% or more as long as:

1) the Table is 53% or less, 2) crown is 40 degrees or more, 3) culet is slightly large or bigger.

However GIA requires this length to be equal or less than 60% in order for a diamond to qualify to be called an OEC.
 

yssie

Super_Ideal_Rock
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20,987
However if anybody wants to prolong the agony, I do have some hints on how to determine a well cut OEC from the GIA certs. :lol-2:
Again. No.
No, you really, really can’t.
You might think you can; you’d be wrong.

For one major reason:
The report tells you nothing about how old the stone actually is or what the cutter’s agenda was, which means you have absolutely no idea what sort of symmetry it boasts.
You can make all the judgments and assumptions that you want, but if your stone does not exhibit symmetry about whatever axes you are judging by, your conclusions are at best meaningless and at worst outright misleading.

This is completely ignoring the fact that without looking at stones in-person you have no idea if what you think you want to see actually is what you want to see.

I enjoy the more academic threads as much as the next PSer, but this thread isn’t purely in aid of academia - at the end of it a consumer is looking to purchase a stone. As such, I’m a little surprised by how one-sided the trade participation in here has been - more practical advice for someone pretty new to the diamond search is certainly merited, IMO. I hope lurkers aren’t getting caught up on the numbers and missing the big picture - for anyone else who might be looking to buy a stone, this thread should serve as warning for how not to approach your own diamond search.
 
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ForteKitty

Ideal_Rock
Joined
Oct 7, 2004
Messages
4,640
Again. No.
No, you really, really can’t.
You might think you can; you’d be wrong.

For one major reason:
The report tells you nothing about how old the stone actually is, which means you have absolutely no idea what sort of symmetry it was cut with.
You can make all the judgments and assumptions that you want, but if your stone does not exhibiting symmetry about whatever axes you are judging by, your conclusions are at best meaningless and at worst outright misleading.
This! So much this. Your assessment was based on taking the average number on the crown and pavilion, with no regard to each crown facet and the relationship it plays with the corresponding pavilion facet, and the relationship it has with opposing facets, which is so, so important. A good old cutter would have accounted for that and modified accordingly, which is why a good old cut is pure magic. They have the ability to "see" it. It's not just one set of numbers because they have to work together.
 

LLJsmom

Ideal_Rock
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9,592
This! So much this. Your assessment was based on taking the average number on the crown and pavilion, with no regard to each crown facet and the relationship it plays with the corresponding pavilion facet, and the relationship it has with opposing facets, which is so, so important. A good old cutter would have accounted for that and modified accordingly, which is why a good old cut is pure magic. They have the ability to "see" it. It's not just one set of numbers because they have to work together.
So simply said yet so clear. Thank you.
 

LLJsmom

Ideal_Rock
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Messages
9,592
Again. No.
No, you really, really can’t.
You might think you can; you’d be wrong.

For one major reason:
The report tells you nothing about how old the stone actually is or what the cutter’s agenda was, which means you have absolutely no idea what sort of symmetry it boasts.
You can make all the judgments and assumptions that you want, but if your stone does not exhibit symmetry about whatever axes you are judging by, your conclusions are at best meaningless and at worst outright misleading.

This is completely ignoring the fact that without looking at stones in-person you have no idea if what you think you want to see actually is what you want to see.

I enjoy the more academic threads as much as the next PSer, but this thread isn’t purely in aid of academia - at the end of it a consumer is looking to purchase a stone. As such, I’m a little surprised by how one-sided the trade participation in here has been - more practical advice for someone pretty new to the diamond search is certainly merited, IMO. I hope lurkers aren’t getting caught up on the numbers and missing the big picture - for anyone else who might be looking to buy a stone, this thread should serve as warning for how not to approach your own diamond search.
Yes, thank you...
 

Lessics

Shiny_Rock
Joined
Jan 6, 2019
Messages
427
@prs I’ve been enjoying this thread so please keep posting. Obviously it’s always the eye that should decide on any diamond (oec or modern), but it’s fun collecting data and playing around with it. Not sure where to do that if not on pricescope.
 

prs

Brilliant_Rock
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@prs, I mean this with no disrespect intended, but have you or DW actually seen - in-person, with your own eyes - any of the stones you have such admiration for photos of? If not these specific specimens - comparisons with similar faceting?

There is an objectively correct way to approach to search with the science and technology that you appreciate:
1. See lots of stones in-person,
2. Identify, in-person, what those stones have in common - what trends, nuances, what particulars consistently draw your eye and your attention?
3. Correlate proportions and light reflector images to the trends and nuances and particulars that you identified in-person.

Only after taking these steps - in this order - can you have confidence that what you look for with technology is in fact what your eyes want to see IRL. No photographs or video can ever comprehensively depict a stone’s character and behaviour across a variety of lighting environments, and when we’re talking about non-standardized shapes and faceting like true antiques... It is VERY possible to fall in love with a patterning that photographs a certain way only to learn that it isn’t quite what you want in-person.

The very nature of PS, an internet medium, makes it easy to put far too much initial trust in photos, videos, design diagrams. PS zeitgeist demands X, therefore it must be best. DiamCalc identifies Y as elite, therefore it must be best. The more willing one is to dive into the technology backing a given recommendation, the easier it is to put faith in that recommendation... The easier it is to prioritize technology over in-person education. And yet, perversely, the more particular one is about what one is looking for - and based on this 9-page thread you, @prs, are a very particular person! - the more critical that in-person learning is.

As another person who has been buying diamonds for a very long time - I urge you to heed @diamondseeker2006's advice. There is no technology that can predict what flavour of OEC you will most enjoy looking at. The only way to find out is to look at stones yourself; to not do so, to disregard the downsides of a primarily-technological approach, is to do yourself and your search a huge disservice.
I had no idea a discussion of facet patterns was going to provoke such strong feelings, and I sincerely apologize to those I offended.

Actually @yssie I do find your post to be disrespectful. Your claim that I intend to buy DW a diamond based entirely on the numbers is just wrong! Of course we have seen, and intend to see lots more stones in person, where exactly in this thread did I say otherwise?

I'm happy that you are "another person who has been buying diamonds for a very long time" and assume you too had to go through a learning curve to get to be the undoubted expert you are. It's beyond me why you feel such contempt for me trying to accelerate my learning curve.


Again. No.
No, you really, really can’t.
You might think you can; you’d be wrong.

For one major reason:
The report tells you nothing about how old the stone actually is or what the cutter’s agenda was, which means you have absolutely no idea what sort of symmetry it boasts.
You can make all the judgments and assumptions that you want, but if your stone does not exhibit symmetry about whatever axes you are judging by, your conclusions are at best meaningless and at worst outright misleading.

This is completely ignoring the fact that without looking at stones in-person you have no idea if what you think you want to see actually is what you want to see.

I enjoy the more academic threads as much as the next PSer, but this thread isn’t purely in aid of academia - at the end of it a consumer is looking to purchase a stone. As such, I’m a little surprised by how one-sided the trade participation in here has been - more practical advice for someone pretty new to the diamond search is certainly merited, IMO. I hope lurkers aren’t getting caught up on the numbers and missing the big picture - for anyone else who might be looking to buy a stone, this thread should serve as warning for how not to approach your own diamond search.
@yssie I find this post to be not only disrespectful, but an insult to my intelligence. You have immediately jumped to the wrong conclusion that I am somehow proposing to use the GIA report to determine the beauty of a particular diamond. Nothing could be further from the truth! You then concluded by giving me another lecture about needing to see more stones in person. The first lecture was quite enough thank you!

If you have such strong feelings about my thread, perhaps it would be best if you didn't click on it any more.
 

yssie

Super_Ideal_Rock
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20,987
I've read all ten pages of this thread.

The last five of those ten pages involve correlating dimensions estimated from photos of other PSers' diamonds (a few with reports) with proportions charts against diamcalc simulations.

Not once in these ten pages have you said "this is a photo of a diamond that I fell for in-person, and let me describe what I loved about it - please simulate this stone".

That tells me everything that you didn't explicitly say about how you're approaching your search; that you disagree with my assessment of your approach doesn't negate the validity of that assessment.

I think you vastly underestimate how "technical" most of us could get, if we wanted to... But @diamondseeker2006, @LLJsmom, @ForteKitty, I’m sure I’ve missed a few people - We are all saying the same thing - and what we've got in common is decades of personal consumer-side experience with dozens, probably hundreds, of stones. And we understand that numbers and software and photos and videos only tell us so much - there is just nothing like seeing in-person.

I will bow out of your thread as you wish, but I caution yet again about believing that this thread is accelerating your learning curve - based on what you've shared in this thread, it's not, because you're skipping the most important part.
 
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prs

Brilliant_Rock
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Back in early January DW expressed an interest in OECs, so on a visit to David Klass we asked if they knew of a someplace we could go see lots of OECs. David had heard that Grace had just gotten in a fabulous OEC and would we like to see it. Well of course it was fabulous, and DW fell in love.

6.19ct 2 (2).jpg

This 6.19ct L was out of our price range, but after looking into MRB pricing on the PS diamond search I figured we should be looking for a stone around 4.5-5.0ct and in the K-L color range. Over the following six weeks we made trips to LA and visited a number of estate jewelry dealers. We found extremely thin pickings in our carat weight range, and we were shown nothing that approached the beauty of Grace's stone. This is the one that came closest, but it faced up much yellower than DW wanted.

4.23ct N,VS (4).jpeg

How is it that some low color stones face up much whiter than others is a question we asked ourselves.

On our last trip a jeweler got a call about a diamond a dealer had just gotten in. It was almost 7ct but only a little over our budget and would we like to see it. The stone was couriered over, and to our uneducated eyes it looked pretty darned good. For a 6.98ct it was a great deal.

6.98ct OEC.jpg

The stone had just come in so there was no GIA, and having learned from PS, I knew we shouldn't ever buy a diamond without a GIA. We couldn't put the diamond on hold long enough for it to sent for a cert, but the jeweler said he could get a Sarine scan very quickly. Here is the result

6.98ct Sarine Scan Results.JPG

I quickly figured out this was not a 6.98ct stone, it was really a 5.5ct stone in disguise! :eek-2::eek-2::eek-2:

This was the moment I knew we needed to know a lot more about OECs!!!!

DW and I are both of retirement age, and one of us has a compromised immune system. A bout with Covid is likely to have an extremely problematic outcome! I know my search for the numbers has ruffled a few feathers, to say the least! However whilst I'm sure your demands we go see lots more diamonds in person are well intentioned, I hope you don't mind if we resist them until it's safe to do so.

I think I know why my search for the numbers has generated such a furious response. The numbers don't fit the myths that surround OECs, more on that later when I have more time.
 

ForteKitty

Ideal_Rock
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Messages
4,640
The second diamond you just posted.. what color was that supposed to be? It looks like a GIA QR. There's a ton of leakage and I'm willing to bet it was shallow with low crown height. That third one is a poorly cut MRB, not old cut at all. I wouldn't say the responses have been "furious". It's just faster to eliminate by eye if you know what to look for, you don't even need to physically be there if they can send a few pics. I'm curious what "myths" you're referring to as well LOL, they're still just diamonds. Also regarding what makes some face up whiter, sometimes it's just the body color. It may not even have to do with the cut itself.
 
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prs

Brilliant_Rock
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The second diamond was supposed to be an N but it didn't have a GIA. The story we heard a couple of times was the Rappaport price list only goes down to M color, so if a dealer has a diamond he knows will be lower, they don't bother getting a GIA. In retrospect I suspect the real reason is they really don't want to know the true color, and can claim they believe it is an N with a clearer conscience. :) Confirming once again you should never buy a diamond without a GIA!!!

Yes the third diamond is an extremely poorly cut MRB. However the scary thing is it wouldn't take much of a re-cut for that diamond to get itself a GIA cert as a "Circular Brilliant". :eek-2:

I know I can recognize a beautiful OEC facet pattern when I see one, but for sure I don't have your expertise to determine from photos how well a diamond might be cut. I wish I could but know that's going to require more experience and take much longer. That's why I am working on using the limited data on the GIA cert to help me figure out Crown and Pavilion angles and depths with reasonable accuracy. This sure wouldn't tell me anything about beauty but it would tell me if the stone had been cut to decent proportions.

If I'm going to help DW find an OEC she loves by the time our 40th comes around, and stay far away from Covid, I'm going to have to learn how to better interpret photos and CIA certs!
 

Karl_K

Super_Ideal_Rock
Trade
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Aug 4, 2008
Messages
10,342
cutting diamonds has always been art but it has also always been science.
From finding good combos to documenting it and passing that information on on to your apprentices to make more of them.
Better ways to measure and control while cutting the important angles has been worked on for a long time.
The science is not as sexy as the art so it gets forgotten at times.
The old wonderful diamond your holding in your hand is certainly the result of art but it is also just as much the result of science.
If someone wants to learn the science there is nothing wrong with that.
 

LLJsmom

Ideal_Rock
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Messages
9,592
The second diamond was supposed to be an N but it didn't have a GIA. The story we heard a couple of times was the Rappaport price list only goes down to M color, so if a dealer has a diamond he knows will be lower, they don't bother getting a GIA. In retrospect I suspect the real reason is they really don't want to know the true color, and can claim they believe it is an N with a clearer conscience. :) Confirming once again you should never buy a diamond without a GIA!!!

Yes the third diamond is an extremely poorly cut MRB. However the scary thing is it wouldn't take much of a re-cut for that diamond to get itself a GIA cert as a "Circular Brilliant". :eek-2:

I know I can recognize a beautiful OEC facet pattern when I see one, but for sure I don't have your expertise to determine from photos how well a diamond might be cut. I wish I could but know that's going to require more experience and take much longer. That's why I am working on using the limited data on the GIA cert to help me figure out Crown and Pavilion angles and depths with reasonable accuracy. This sure wouldn't tell me anything about beauty but it would tell me if the stone had been cut to decent proportions.

If I'm going to help DW find an OEC she loves by the time our 40th comes around, and stay far away from Covid, I'm going to have to learn how to better interpret photos and CIA certs!
Why don't you request videos? I find those much more helpful than photos. As you know, Grace does a ton of them. Have you reached out to Adam at OWD? Don't just go by the videos he has on the website or on Youtube. If you haven't already, talk to him and tell him your parameters. He has a great eye and can send you videos of stones that he thinks are beautiful. You can put a deposit down and he will send you certain stones in ring holders. If you don't like it, send it back. I am not the only PSer that has done that.
 

prs

Brilliant_Rock
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Just came across a GIA article that describes how they arrived at the cut characteristics for their three different types of round diamonds. It was published in 2013 which I think is the year they added the "Circular Brilliant" designation.

The article includes a video that does a great job of capturing the facet patterns of each type of stone. Here's a screenshot from the video

GIA Round Diamond Facet Pattern Comparison Photo.png

They describe the cut details of each type

GIA Old European Facet Photo and Cut Description.png

They point out that Old Europeans were cut with small tables, and steep crowns, and that short lower halves gave a "blocky" facet pattern. There is no flower petal pattern. This is consistent with rounds cut a hundred years ago with crown angles greater than 40° and lower half lengths around 30%.

GIA Circular Brilliant Facet Photo and Cut Description.png

Their Circular Brilliant has a slightly larger table and it does have a flower petal pattern, but GIA still say the short lower halves give a "blocky" pattern. I am coming to the conclusion that back then GIA had not realized there was such a thing as the "flower petal" pattern, nor that it would become so popular with old cut connoisseurs. If they had, they could easily have adjusted their specs on lower half lengths to allow for different size tables.

GIA Modern Brilliant Facet Photo and Cut Description.png

Lastly, they describe the MRB facet pattern as "splintery". I'm guessing the guy who came up with that description was not in sales. :mrgreen2:

Here's a LINK to the article.
 
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ForteKitty

Ideal_Rock
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That link has been posted here many times before! We reference it frequently whenever people have questions about how GIA came to their assessment. It wasn't already linked here?

What a terrible computer generated image of an european cut... the center looks like a puckered anus. None of my GIA designated oecs look like that, thank goodness. The "flowery pattern" term was probably a PSer's invention, lol.
 
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prs

Brilliant_Rock
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DW has worn her 2.05ct MRB every day since our 25th in 2006. I took a close look at it the other day with my loupe and was amazed to find it had a beautiful hearts and arrows pattern. How could we have gone fourteen years without noticing that. :eek-2: Maybe because at 35.5°, 41.2° the contrast isn't enough to highlight the pattern, or maybe because our eyes aren't as sharp as they once were?

Anyway this prompted DW to ask me what the facet pattern on her OEC was going to look like in real life. I was able to shrink my facet diagrams down closer to life size without losing too much definition

Left: Table: 45%, LGF: 60%
Center: Table: 50%, LGF: 60%
Right: Table: 53%, LGF: 60%
OEC6.3% Fig 10A T45,50,53 S30,35,40 L60,60,60.png

Left: Table: 45%, LGF: 65%
Center: Table: 50%, LGF: 65%
Right: Table: 53%, LGF: 63%
OEC6.3% Fig 10B T45,50,53 S30,35,40 L65,65,63.png

Left: Table: 53%, LGF: 63%
Center: Table: 56%, LGF: 63%
Right: Table: 59%, LGF: 63%
OEC6.3% Fig 10C T53,56,59 S40,45,50 L63,63,63.png

Previously she had picked 50% as her preferred table size, but after looking at these views she found the 53% table pattern much easier to see. The 56% and 59% table sizes are also not completely out of the reckoning. I might try increasing the Lowers to 65% or even 67% to see if that gives a stronger, more easily viewed pattern. Food for thought. :)
 
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ForteKitty

Ideal_Rock
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Okay, I hate to be the one to naysay all the time, but...

Those charts don't look accurate to me. Visually. I had a 39% table oec, don't remember depth, but the petals looked about the same size as the 45%/65%. I had another with 42% table and it also looked like the 45%. Also I have several around 50-51% tables that look similar to the 59% in your pictures.

Point being, there are other factors besides the two you accounted for, so please show them drawings of what she likes, and have the vendor find ones that fit. Many vendors don't have sarins on their stones, so selecting based on LGF will severely limit your options.
 

prs

Brilliant_Rock
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Dear ForteKitty, it would take you all of two minutes to check if my facet diagrams are accurate. Just print them out, and then take a ruler with a mm scale and measure them. The full size diagrams can be found on Page 9, posts 269 and 252. If you need instructions on how to use a ruler, just ask and I will be happy to help.

Once you've done that please get back to me with any inaccuracies you've found.

If you find the diagrams are accurate, perhaps it's time to admit you don't have a clue when it comes to the numbers. You most certainly have a great eye for beauty and all your pieces are drop dead gorgeous. However plucking numbers out of thin air doesn't make them true. This is not rocket science, all it takes is a ruler to figure out most of these numbers. No matter how much you and some of the others dislike them, the numbers are the numbers.

I'm sorry if I've ruffled some feathers by discovering that 120 year diamonds with their steep crown angles and short 30% Lowers can't possibly have a flower petal pattern. However this doesn't mean your diamond isn't 100 years old. Henry Morse was making diamonds with lower crown angles and longer Lowers as early as the 1880s. For sure the cutters who were on the leading edge of innovation in the early 1900s must have recognized the beauty of the flower petal pattern.

I had decided life was too short to put up with all these misinformed, nasty, mean spirited posts, but then I realized this thread had got over a thousand views since my last set of posts. I'm glad there are still some people here interested in learning new things, so maybe I'll soldier on for a little while longer. :mrgreen2:
 

jaaron

Brilliant_Rock
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Dear ForteKitty, it would take you all of two minutes to check if my facet diagrams are accurate. Just print them out, and then take a ruler with a mm scale and measure them. The full size diagrams can be found on Page 9, posts 269 and 252. If you need instructions on how to use a ruler, just ask and I will be happy to help.

Once you've done that please get back to me with any inaccuracies you've found.

If you find the diagrams are accurate, perhaps it's time to admit you don't have a clue when it comes to the numbers. You most certainly have a great eye for beauty and all your pieces are drop dead gorgeous. However plucking numbers out of thin air doesn't make them true. This is not rocket science, all it takes is a ruler to figure out most of these numbers. No matter how much you and some of the others dislike them, the numbers are the numbers.

I'm sorry if I've ruffled some feathers by discovering that 120 year diamonds with their steep crown angles and short 30% Lowers can't possibly have a flower petal pattern. However this doesn't mean your diamond isn't 100 years old. Henry Morse was making diamonds with lower crown angles and longer Lowers as early as the 1880s. For sure the cutters who were on the leading edge of innovation in the early 1900s must have recognized the beauty of the flower petal pattern.

I had decided life was too short to put up with all these misinformed, nasty, mean spirited posts, but then I realized this thread had got over a thousand views since my last set of posts. I'm glad there are still some people here interested in learning new things, so maybe I'll soldier on for a little while longer. :mrgreen2:
I don't have a dog in this fight, as the saying goes. And I'm sorry if you've found the posts mean-spirited and nasty (I confess to not having read the whole thing), but I do want to point out, as a PS visitor who likes OECs but is by no means an expert, that it might also be worth considering whether some of those 1000+ views could be to see if you are interested in learning new things. i.e. that an eye for beauty might be equally, if not more, important than the numbers when it comes to identifying the perfect oec.

You're obviously very mathematically/engineering oriented, and I think it's great that you're enjoying/involving yourself in this project, and I think there are quite a few people who enjoy the calculations, which is also great. But your way is only one way to approach things, and what feels like an insistence on it being *the* way, comes off as a bit mansplainy to me.

After all isn't this, the drop dead gorgeous part, the most important thing?
You most certainly have a great eye for beauty and all your pieces are drop dead gorgeous.
 

prs

Brilliant_Rock
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I don't have a dog in this fight, as the saying goes. And I'm sorry if you've found the posts mean-spirited and nasty (I confess to not having read the whole thing), but I do want to point out, as a PS visitor who likes OECs but is by no means an expert, that it might also be worth considering whether some of those 1000+ views could be to see if you are interested in learning new things. i.e. that an eye for beauty might be equally, if not more, important than the numbers when it comes to identifying the perfect oec.

You're obviously very mathematically/engineering oriented, and I think it's great that you're enjoying/involving yourself in this project, and I think there are quite a few people who enjoy the calculations, which is also great. But your way is only one way to approach things, and what feels like an insistence on it being *the* way, comes off as a bit mansplainy to me.

After all isn't this, the drop dead gorgeous part, the most important thing?
You most certainly have a great eye for beauty and all your pieces are drop dead gorgeous.
You seem to be assuming that because I'm good with numbers, I don't have an appreciation for beauty. In fact if you look at the OECs I have linked in the thread or at the colored stone pieces DW and I have purchased together, you will see that I too have an eye for beauty.

OECs of the size, color, and clarity we are looking for are few and far between. They are so rare that the asking prices for the most beautiful ones have huge mark ups. It's looking more and more like we are going to have to recut an ugly stone into a thing of beauty. In order to do that I need to know the numbers that make a beautiful OEC. That's why this thread exists.

If someone isn't interested in the numbers and prefers to remain in blissful ignorance, why don't they just stop clicking on this thread?
 

jaaron

Brilliant_Rock
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Messages
803
I'm not assuming that at all. But I do feel like you're assuming that there's nothing you can learn from people like @ForteKitty and @diamondseeker2006 and @missy who have chosen stunning OECs by the visuals.

I guess I think of it like this. You could graph your wife's face to map it against the perfect scientifically determined standards of human beauty. It's possible she meets those standards, but it's also possible that she doesn't and there are still things you saw in her that were indefinable and unquantifiable that made you find her beautiful and fall in love with her. By the same token, it's perfectly possible you could have met someone who was the apotheosis of those standards but left you cold because the indefinables and unquantifiables weren't right for you.

I'm not calling you out, just trying to explain what I'm seeing.
 

ForteKitty

Ideal_Rock
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Messages
4,640
Dear ForteKitty, it would take you all of two minutes to check if my facet diagrams are accurate. Just print them out, and then take a ruler with a mm scale and measure them. The full size diagrams can be found on Page 9, posts 269 and 252. If you need instructions on how to use a ruler, just ask and I will be happy to help.

Once you've done that please get back to me with any inaccuracies you've found.

If you find the diagrams are accurate, perhaps it's time to admit you don't have a clue when it comes to the numbers. You most certainly have a great eye for beauty and all your pieces are drop dead gorgeous. However plucking numbers out of thin air doesn't make them true. This is not rocket science, all it takes is a ruler to figure out most of these numbers. No matter how much you and some of the others dislike them, the numbers are the numbers.

I'm sorry if I've ruffled some feathers by discovering that 120 year diamonds with their steep crown angles and short 30% Lowers can't possibly have a flower petal pattern. However this doesn't mean your diamond isn't 100 years old. Henry Morse was making diamonds with lower crown angles and longer Lowers as early as the 1880s. For sure the cutters who were on the leading edge of innovation in the early 1900s must have recognized the beauty of the flower petal pattern.

I had decided life was too short to put up with all these misinformed, nasty, mean spirited posts, but then I realized this thread had got over a thousand views since my last set of posts. I'm glad there are still some people here interested in learning new things, so maybe I'll soldier on for a little while longer. :mrgreen2:
Omg LMAO are we assuming I can't math? I will refrain from snark about not knowing how to use a ruler, even though it's so against my nature. My engineer husband would laugh at the thought of me not knowing my measurements, because I called him out from 35ft away for hanging the curtain rod 5mm lower on one end. :lol-2:

I never said the mm isn't accurate and the diagrams aren't correct. What I said, was the visuals aren't entirely right. Did you even read that? It doesn't look accurate because those diagrams you keep posting are FLAT. You do realize there are often height differences between the girdle the the table height, right? A diamond with 51% table at, say 1.5mm, will VISUALLY look different than a 51% table that's 1mm away from the girdle. The 1.5mm height will LOOK much bigger, even though both are 51%. That's what I'm trying to say, and I thought I was being quite nice. Diamonds are 3D and you have to account for the crown height in 3D. A flat diagram doesn't LOOK the same as a live, 3D diamond. Sure, they draw the lines to curve a bit more if the height is greater, but the diagram is still flat. C'mon, if you're good with numbers you should already know that.

Assuming a flat diagram of a diamond has the same visuals as a 3D stone is inaccurate, period. Nothing nasty about it. Why do you think cutters have programs that generate a 3D view?

What is the feather ruffling you keep talking about? Who cares if it's 100 years old or not. Why do you assume we only want old old stones? Most of us were trying to tell you a set of numbers and a flat diagram alone aren't enough math because you didn't use ENOUGH numbers. You need more numbers and 3D. How many times have I suggested there are other factors? C'mon dude. This is what we get for being nice to people online.

ETA: the earlier post's table % weren't pulled from thin air, they had GIAs.
 
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yssie

Super_Ideal_Rock
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20,987
Most of us were trying to tell you a set of numbers and a flat diagram alone aren't enough math because you didn't use ENOUGH numbers. You need more numbers and 3D. How many times have I suggested there are other factors?
This.

@ForteKitty has likely personally seen, handled, owned more OECs and OMCs than any other consumer and most vendors here on PS. Her opinions and recommendations are borne of both education and personal experience. We already know you can't say the same.

Your numbers are a fantastic example of "garbage in, garbage out" because you are not considering all the numbers that need to be considered, and you are not giving those other variables sufficient gravitas to lend your book-learnt estimations any real-world credence.

Unless you choose a new precision-cut, or you do go the recut route, you will not have access to all the numbers that need to be considered. Frankly, even if you do have access to all the numbers, your months-long foray into ghosts of threads past here on PS doesn't actually make you an expert on faceting and patterning. Dear @prs, I realize this must be distressing to hear, given how tightly you've clung to that misguided presumption - your inflated opinion of yourself and your math skillz is truly astonishing. (Is there where I'm supposed to post my own advanced degrees and qualifications?)

I'm confident lurkers reading this thread will walk away with the intended messaging. For the rest of us - the only outcome to banging one's head against a brick wall is a sore skull.
 
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ForteKitty

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This.

@ForteKitty has likely personally seen, handled, owned more OECs and OMCs than any other consumer and most vendors here on PS. Her opinions and recommendations are borne of both education and personal experience. We already know you can't say the same.

Your numbers are a fantastic example of "garbage in, garbage out" because you are not considering all the numbers that need to be considered, and you are not giving those other variables sufficient gravitas to lend your book-learnt estimations any real-world credence.

Unless you choose a new precision-cut, or you do go the recut route, you will not have access to all the numbers that need to be considered. Frankly, even if you do have access to all the numbers, your months-long foray into ghosts of threads past here on PS doesn't actually make you an expert on faceting and patterning. I realize this must be distressing to hear, given how tightly you've clung to that misguided presumption - your inflated opinion of yourself and your math skillz is truly astonishing. (Is there where I'm supposed to post my own advanced degrees and qualifications?)

I'm confident lurkers reading this thread will walk away with the intended messaging. For the rest of us - it's obviously time for popcorn.
Don't forget each of the crown facets in a single diamond can vary in width and aren't identical in size, as the diagrams assumes. So many varying factors that can affect visuals! Just two crown facets slightly off from the diagram can yield different light reflection and change appearance, but the table and LGF will remain the same so on paper, so people think it should look the same-- but it wont. Girl, I actually took out my calipers, boxes of diamonds and bag of GIAs... there's like 40+ GIA reports here and I even have some sarins. But I'm eating popcorn instead and watching football. :twisted2:
 
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yssie

Super_Ideal_Rock
Premium
Joined
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Messages
20,987
Don't forget each of the crown facets in a single diamond can vary in width and aren't identical in size, as the diagrams assumes. So many varying factors that can affect visuals! Girl, I actually took out my calipers, boxes of diamonds and bag of GIAs... there's like 40+ GIA reports here and I even have some sarins. But I'm eating popcorn instead and watching football. :twisted2:
Oh, I know. Or - I can guess, having known you for as long as I have :bigsmile:
And it's worth posting the memo to that effect here so that lurkers get a balanced view of reality.
But yeah, as far as OP is concerned, popcorn and football seems like a better use of sanity at this point - forcing horses to drink and all that ::)
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
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Messages
15,670
Just came across a GIA article that describes how they arrived at the cut characteristics for their three different types of round diamonds. It was published in 2013 which I think is the year they added the "Circular Brilliant" designation.

The article includes a video that does a great job of capturing the facet patterns of each type of stone. Here's a screenshot from the video

GIA Round Diamond Facet Pattern Comparison Photo.png

They describe the cut details of each type

GIA Old European Facet Photo and Cut Description.png

They point out that Old Europeans were cut with small tables, and steep crowns, and that short lower halves gave a "blocky" facet pattern. There is no flower petal pattern. This is consistent with rounds cut a hundred years ago with crown angles greater than 40° and lower half lengths around 30%.

GIA Circular Brilliant Facet Photo and Cut Description.png

Their Circular Brilliant has a slightly larger table and it does have a flower petal pattern, but GIA still say the short lower halves give a "blocky" pattern. I am coming to the conclusion that back then GIA had not realized there was such a thing as the "flower petal" pattern, nor that it would become so popular with old cut connoisseurs. If they had, they could easily have adjusted their specs on lower half lengths to allow for different size tables.

GIA Modern Brilliant Facet Photo and Cut Description.png

Lastly, they describe the MRB facet pattern as "splintery". I'm guessing the guy who came up with that description was not in sales. :mrgreen2:

Here's a LINK to the article.
Excellent link - Thx prs
It's a bit rude that they did not declare the videos were made with DiamCalc (disclosure - I am the agent).
 

ForteKitty

Ideal_Rock
Joined
Oct 7, 2004
Messages
4,640
Oh, I know. Or - I can guess, having known you for as long as I have :bigsmile:
And it's worth posting the memo to that effect here so that lurkers get a balanced view of reality.
But yeah, as far as OP is concerned, popcorn and football seems like a better use of sanity at this point - forcing horses to drink and all that ::)
Niners are sucking and C is stressed out. The popcorn is for watching him too, haha.
 

yssie

Super_Ideal_Rock
Premium
Joined
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Messages
20,987
cutting diamonds has always been art but it has also always been science.
From finding good combos to documenting it and passing that information on on to your apprentices to make more of them.
Better ways to measure and control while cutting the important angles has been worked on for a long time.
The science is not as sexy as the art so it gets forgotten at times.
The old wonderful diamond your holding in your hand is certainly the result of art but it is also just as much the result of science.
If someone wants to learn the science there is nothing wrong with that.
There is nothing at all wrong with wanting to learn the science.

But
1. Taking rulers to printouts ain’t “science”,
2. There is actually a lot wrong with basing a purchase primarily on a half-baked comprehension of the science, which is all OP boasts right now, and
3. There is a lot more wrong with encouraging others to do the same.

#2, and especially #3, are what we long-time consumers are objecting to in this thread. #1 is just entertaining as a spectacular display of inflated ego.
 

LLJsmom

Ideal_Rock
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Joined
Oct 24, 2012
Messages
9,592
Dear ForteKitty, it would take you all of two minutes to check if my facet diagrams are accurate. Just print them out, and then take a ruler with a mm scale and measure them. The full size diagrams can be found on Page 9, posts 269 and 252. If you need instructions on how to use a ruler, just ask and I will be happy to help.

Once you've done that please get back to me with any inaccuracies you've found.

If you find the diagrams are accurate, perhaps it's time to admit you don't have a clue when it comes to the numbers. You most certainly have a great eye for beauty and all your pieces are drop dead gorgeous. However plucking numbers out of thin air doesn't make them true. This is not rocket science, all it takes is a ruler to figure out most of these numbers. No matter how much you and some of the others dislike them, the numbers are the numbers.

I'm sorry if I've ruffled some feathers by discovering that 120 year diamonds with their steep crown angles and short 30% Lowers can't possibly have a flower petal pattern. However this doesn't mean your diamond isn't 100 years old. Henry Morse was making diamonds with lower crown angles and longer Lowers as early as the 1880s. For sure the cutters who were on the leading edge of innovation in the early 1900s must have recognized the beauty of the flower petal pattern.

I had decided life was too short to put up with all these misinformed, nasty, mean spirited posts, but then I realized this thread had got over a thousand views since my last set of posts. I'm glad there are still some people here interested in learning new things, so maybe I'll soldier on for a little while longer. :mrgreen2:
Pot... I’d like to introduce you to Kettle...
 
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