Teach Me!

[snaphappy]

I have so many questions!! But AI is not really answering this one. So here goes.

On the internet, when I’m looking at brilliant round (assuming no leds are present) I see a lot of black, a lot of blue maybe, sometimes just in the center, sometimes the entire diamond.

Keep in mind, our diamonds are both in that j-m range, one is OEC and the other is transitional, both have culets.

So in the RBC am I seeing spears, or hearts and arrows?
Am I seeing D-I color and my eye is interpreting that as blue?
Am I seeing scintillation? And maybe old cuts like ours don't have scintillation because we don't have spears, or hearts and arrows?
Am I noticing this simply because the RBC has a MUCH bigger table than our diamonds?
Oh another question, does a culet stop this from happening?

 

[Karl_K]

Many of the colors in 360 video are enviromental.
Blue from shirts or uniforms is very common as is brown and yellow.

Many sites use a still shot of the 360vid for the static picture.

 

[snaphappy]

Ok they're not called spears. You guys call them arrows? I think the larger table allows me to see the arrows. And the arrows look black to me. I’m guessing the arrows are there in my wife’s transition cut, but maybe I can’t see them because the table is so small? Or the culet keeps me from seeing them? Or maybe both?

Here’s a video. Without perfect led lighting, all RBC diamonds look black and dark to me…

 

[Karl_K]

This might help you understand the difference between an oec and mrb.

Do the pavilion mains drive light return in the modern round brilliant?

Article by Karl K. On many websites you will see it said that the pavilion main facets drive light return. Top labs and many grading systems use the pavilion angle […]

www.pricescope.com

 

[Karl_K]

This in particular.

The reflection of the facets in red are the arrows. (pavilion mains)
In the oec they are the entire under table area.
They are cut to react to obstruction more in a modern RB than a cut for a ring oec or transitional.
If an oec reacted to obstruction and many do the same as modern RB they would appear dark in a ring at some distances.
However in a tiara or pendant they would be awesome.
The viewing distance is what changes and makes the difference.
Many videos are the same as viewing the diamond at 4-5 inches from your eye so obstruction is not representative.

 

[Garry H (Cut Nut)]

This in particular.

The reflection of the facets in red are the arrows. (pavilion mains)
In the oec they are the entire under table area.
They are cut to react to obstruction more in a modern RB than a cut for a ring oec or transitional.
If an oec reacted to obstruction and many do the same as modern RB they would appear dark in a ring at some distances.
However in a tiara or pendant they would be awesome.
The viewing distance is what changes and makes the difference.
Many videos are the same as viewing the diamond at 4-5 inches from your eye so obstruction is not representative.

Excellent explanation Karl!

 

[snaphappy]

I'm kinda slow. So bigger table = bigger obstruction? So my head is obstructing the light... and the table is bigger on the RBC... so it looks like a bigger dark area?

So if I view an RBC from across the room, with no obstruction, it will look magical? Interesting!

If I understand all of this correctly, it's perplexing that RBC dominates wedding rings. Hand is the only jewel you can obstruct so it seems like an odd place to put an RBC

 

[Karl_K]

I think your confusing video appearance with real world appearance.
In the video shown its a lighting issue not a diamond issue.
Someone would have to work very hard to ever see that diamond look like that to the bare eye.

A well cut RB has balanced contrast up close at a reasonable distance and not over responsive to obstruction at extended distances which makes them look less bright.
It is a balance.

 

[snaphappy]

I think your confusing video appearance with real world appearance.
In the video shown its a lighting issue not a diamond issue.
Someone would have to work very hard to ever see that diamond look like that to the bare eye.

A well cut RB has balanced contrast up close at a reasonable distance and not over responsive to obstruction at extended distances which makes them look less bright.
It is a balance.

Maybe your right! I’ve never had one on my finger. Ok I need try one on haha

 

[snaphappy]

I have lots of questions. Here’s a new one. We noticed in direct sunlight our diamonds look dark. I reproduced this effect with a flashlight. It seems like direct light darkens diamonds. At the same time, when we turn off our bright overhead lights, and our room is lit by a single lamp, our diamonds turn white. My diamond in particular, which is much like a european cut, turns white in low light! Are these phenomena easy to explain? Seems so fascinating! Here’s some pics of my old diamond

 

[Garry H (Cut Nut)]

I have lots of questions. Here’s a new one. We noticed in direct sunlight our diamonds look dark. I reproduced this effect with a flashlight. It seems like direct light darkens diamonds. At the same time, when we turn off our bright overhead lights, and our room is lit by a single lamp, our diamonds turn white. My diamond in particular, which is much like a european cut, turns white in low light! Are these phenomena easy to explain? Seems so fascinating! Here’s some pics of my old diamond

That is a great indication of top cut quality.
Go to the very end of this long explanation of fluorescence please:

Fluorescence

As blue is the complimentary colour to yellow, the most common colour in diamonds, blue fluorescence can make yellow diamonds look white or colourless.

www.hollowaydiamonds.com.au

 

[snaphappy]

Interesting! AI told me constant light from the sun does not allow any fluctuations in light in or out of the diamond. And sparkle and glow happen because of fluctuation. I think it might have mentioned contrast too. A pretty diamond means I’m seeing contrast, but full sun or a flashlight = no contrast

 

[snaphappy]

I read your whole article!! Brilliant! So much info. Do you have more articles? Or a book? Would be wonderful to read a whole book about this. I’m currently reading Stoned

 

[freddyboston]

Garry does have a book..... it's excellent !


Avail in Kindle or Paperback on Amazon

Amazon.com

 

[Dreamer_D]

I would suggest you stop using AI as it is presenting you with a lot of poor information lol

 

[snaphappy]

Garry does have a book..... it's excellent !


Avail in Kindle or Paperback on Amazon

Amazon.com

I usually prefer physical books, but the physical book is $57. You think the physical is worth it? Or just get the kindle for $10?

 

[LightBright]

I read your whole article!! Brilliant! So much info. Do you have more articles? Or a book? Would be wonderful to read a whole book about this. I’m currently reading Stoned

You could also look at past historical threads on Pricescope for discussions on cut. Many original members (including the posters who responded here, are professionals in that area so have posted many technical educational comments.

The book American Cut by Al Gilbertson is also linked for free in one of the threads. You can search. Paper copy is here, I’ve bought my own copy.

Amazon.com

 

[LightBright]

That is a great indication of top cut quality.
Go to the very end of this long explanation of fluorescence please:

Fluorescence

As blue is the complimentary colour to yellow, the most common colour in diamonds, blue fluorescence can make yellow diamonds look white or colourless.

www.hollowaydiamonds.com.au

Also, here’s an informative thread Garry H once did on spot lighting (like a halogen light) turning diamonds dark.

I wonder if it’s not only fluorescence but modern-style ideal (low crown) cuts? that black out in spot lighting.

I think it’s two different things? 1) Blackout under spot lights which doesn’t require flourescence, 2) and Flourescence in sunlight or UV, turning the fluorescent stone dark blue

Thread 'Why your diamond goes dark or blue in direct sunlight'

Dec 23, 2018

There has been another discussion about this topic, and the idea that Fluorescence plays a part. So I did a small test today with various different cuts.

Shaded daylight at 11am, close to the solstice, in Melbourne taken just now on 24th December. The shade is from my body. My hand was vertical and you can see me in the wedding ring and the blue cloudless sky. Its a hot day +30C 90F.

Note in direct sunlight the ideal-cut...

• Garry H (Cut Nut)
• Replies: 75
• Forum: RockyTalky (Diamond Discussion)

• 

 

[Garry H (Cut Nut)]

Interesting! AI told me constant light from the sun does not allow any fluctuations in light in or out of the diamond. And sparkle and glow happen because of fluctuation. I think it might have mentioned contrast too. A pretty diamond means I’m seeing contrast, but full sun or a flashlight = no contrast

That is pure hallucination!!!

 

[snaphappy]

That is pure hallucination!!!

Just another good reason to buy your book!

 

[snaphappy]

Oh but one more question here, is it fair to say a RBC reflects more sky than OEC because the RBC has a larger table? And therefore an RBC would look darker in direct sun than an OEC?

 

[Garry H (Cut Nut)]

Oh but one more question here, is it fair to say a RBC reflects more sky than OEC because the RBC has a larger table? And therefore an RBC would look darker in direct sun than an OEC?

The order of impact:
Pavilion angle
Pavilion Main Length
Crown angle
Indexing
Table size
Girdle thickness

 

[snaphappy]

The order of impact:
Pavilion angle
Pavilion Main Length
Crown angle
Indexing
Table size
Girdle thickness

The ebook was excellent! Learned a lot. Especially about fire. Buying the physical edition next so I can re-read and put in tabs on my favorite sections.

I’m chiefly interested in antique hand (poorly?) cut diamonds. But still learned so so much!

 

[Garry H (Cut Nut)]

The ebook was excellent! Learned a lot. Especially about fire. Buying the physical edition next so I can re-read and put in tabs on my favorite sections.

I’m chiefly interested in antique hand (poorly?) cut diamonds. But still learned so so much!

Thanks Snaphappy,
Glad it helps you on your journey.
BTW we are thinking of starting a gem/diamond photography forum - watcha think bout that?

 

[snaphappy]

Thanks Snaphappy,
Glad it helps you on your journey.
BTW we are thinking of starting a gem/diamond photography forum - watcha think bout that?

I think it's a good idea and people here would enjoy it.

But if you're looking to expand your brand and make more money... I strongly suggest a youtube channel. Be warned, youtube is a lot of work.

But Gary you have the right accent and demeanor. You've heard of stage presence? You have natural youtube presence. Most jewelers don't have a good voice or look. They're very technical, brilliant even, but lack charisma.

You did the proper thing for 2000-2010 by starting this forum and writing books. But to reach a younger audience you need videos, and lots of them, never pictures. And diamonds do SO WELL with video.

When you mentioned a diamond cutting contest on Rappaport's youtube channel I think you were really on to something. This contest, preferably named after you, would tie into your youtube channel brialliantly.

Finally, look into Google's earnings calls/reports. You'll see ALARMING statistics for youtube. Incomprehensible hours watched, paid youtube subscribers increasing every quarter, ad revenue from youtube off the charts, and people under 25 consume more youtube than Netflix, Paramount etc combined.

 

[Garry H (Cut Nut)]

I think it's a good idea and people here would enjoy it.

But if you're looking to expand your brand and make more money... I strongly suggest a youtube channel. Be warned, youtube is a lot of work.

But Gary you have the right accent and demeanor. You've heard of stage presence? You have natural youtube presence. Most jewelers don't have a good voice or look. They're very technical, brilliant even, but lack charisma.

You did the proper thing for 2000-2010 by starting this forum and writing books. But to reach a younger audience you need videos, and lots of them, never pictures. And diamonds do SO WELL with video.

When you mentioned a diamond cutting contest on Rappaport's youtube channel I think you were really on to something. This contest, preferably named after you, would tie into your youtube channel brialliantly.

Finally, look into Google's earnings calls/reports. You'll see ALARMING statistics for youtube. Incomprehensible hours watched, paid youtube subscribers increasing every quarter, ad revenue from youtube off the charts, and people under 25 consume more youtube than Netflix, Paramount etc combined.

Wonderful advice - my wife is videoing me today for a diamond lab bashing talk to the Aussie GAA federal conference.
She will chop it up into 5 or 6 videos for YT - Thanks!

 

[freddyboston]

"CutNut smashes a diamond - with a hammer".... really deserves more views​

where else can you see this ?

 

[lulu_ma]

The ebook was excellent! Learned a lot. Especially about fire. Buying the physical edition next so I can re-read and put in tabs on my favorite sections.

I’m chiefly interested in antique hand (poorly?) cut diamonds. But still learned so so much!

There are a lot of old cut lovers here!

 

[snaphappy]

New question!

If the GIA color graded diamonds face up, as Gary suggests, would there be more D color diamonds in the world?

 

[Garry H (Cut Nut)]

New question!

If the GIA color graded diamonds face up, as Gary suggests, would there be more D color diamonds in the world?

Yes and NO! Depending on cut quality - the shorter the ray paths through a diamond the less color will be seem face up.
Perfect rounds have very short ray paths, averaging around 2.5 time diameter.
Diamonds cut to increase color have three time avg ray path lengths.
Most fancy shapes have poor light return and so they show lower colors.
The round and cushion shown are digital and have identical material color!