Experts opinions needed - Is this a yield issue?

[Stephan]

Date: 8/29/2008 5:01:59 PM
Author: strmrdr
If 40.8 and 41 are both well matched to the crown with the same lgf% there is little if any visible difference going from one to the other.

But I think that 40.8 pavilion would be a better match for a 33.5 pavilion and that a 41 pavilion will be better with a 33 crown.
And if for you both pavilions are equal, then the 40.8 would be a better choice because of the spread.
I''ve once had a diamond with 59.5% depth, 58% table, 33.7 crown, 43% pavilion, stars +/- 60%, lgf about 80%, and it looked better than any H&A - AGS0 I saw, the fire was omnipresent.

The real problem is that I don''t know any tool that can measure fire like the Idealscope measures light return.
Face-up views don''t tell a lot about fire, fire should always be analyzed by tilting a diamond.
I have an Infinity, an EightStar; I had a New Line ACA and I saw Classic ACA''s, all have a different type of fire, and some have (much) more.
Jonathan''s videos are the best representation of differences in fire, and that''s really not enough.
I think Dave Atlas wrote a long time ago on this forum something like: "fire is not important when evaluating a diamond because it''s not predictable", or something like that.
I really don''t agree.
I do agree with Garry H. by preferring slightly shallow diamonds to the common H&A''s, but then again I don''t agree with him when he says that minor facets are not important.
I think most H&A''s on the market are not bargains, because of the high price and the to big importance given to light return by steep/deep combo''s (understand for example 34.8/40. that kill fire/scintillation.
Also remember, who thinks about diamonds thinks money: Brian once pointed out that by choosing a 40.7-40.8 pavilion (his preference), he was loosing I don''t remember what yield percentage to obtain more beauty. But only one percent of BlueNile''s yearly sale would make me happy.
So try to imagine how much money would be lost if the ideal combo becomes 33.5/40.8, long stars, long lgf''s with a 56% table.

 

[strmrdr]

actually with a 55-56 table and 34 crown 41 is likely the closest thing to the best possible match but 40.8 is close.
With a 60% table then it falls somewhere around 33/41.

33/41/55T/80lgf would be down on dispersion more than the ugf/stars can make up for.

 

[strmrdr]

"34.8/40. that kill fire/scintillation"

Proving that statement wrong is well beyond what will fit in this thread and well beyond the understanding of any but 5 or 6 people reading this but it is wrong.

Your personal preference in your preferred lighting environment with your eyesight may like other combos better for you but that does not make them better.

 

[Stephan]

Here some sentences Dave Atlas wrote about fire in the past:

"One chooses a good looking diamond based on other components first. A secondary component is how well fire is seen in the environment you wish to view it in. Every well cut diamond will have sufficient fire in lighting which promotes its occurrence."

or

"I relegate "fire" as a secondary attribute of beauty. Brilliance, Sparkle and Intensity (light Return, scintillation and contrast) are the PRIMARY measures of light behavior."

I REALLY don''t agree.
Scintillation will only be nice if the fire is great.
I think he said that because there is no tool to measure fire.

 

[strmrdr]

Date: 8/29/2008 6:07:15 PM
Author: QueenMum
Here some sentences Dave Atlas wrote about fire in the past:


''One chooses a good looking diamond based on other components first. A secondary component is how well fire is seen in the environment you wish to view it in. Every well cut diamond will have sufficient fire in lighting which promotes its occurrence.''


or


''I relegate ''fire'' as a secondary attribute of beauty. Brilliance, Sparkle and Intensity (light Return, scintillation and contrast) are the PRIMARY measures of light behavior.''

I REALLY don''t agree.

Scintillation will only be nice if the fire is great.

I think he said that because there is no tool to measure fire.

I love white light scintillation too.
Both are kicken.

 

[Stephan]

Date: 8/29/2008 6:04:00 PM
Author: strmrdr
Your personal preference in your preferred lighting environment with your eyesight may like other combos better for you but that does not make them better.

Do you see scintillation under other lighting than direct lighting?

Does the dispersion of a diamond catch the eye of someone that is walking at the other side of the street if there is no sun?

No.

The only thing you can see under "north" lighting without direct sun is light return.

Yes, you can have some scintillation ore dispersion under a tree, but it won''t catch the eye of someone that''s 30 feet away from you, even if it''s mesmerizing for the one who wears that ring.

Yes, the New Line ACA I had before (34.9/40.7) did have some incredible big flashes of fire, but not as much as the 33.7/40.8/58T I had before, and the flashes didn''t go as far (for example 15 feet away from a mirror with lights above it, but in a dark room).

 

[strmrdr]

Date: 8/29/2008 6:07:15 PM
Author: QueenMum
Here some sentences Dave Atlas wrote about fire in the past:


''One chooses a good looking diamond based on other components first. A secondary component is how well fire is seen in the environment you wish to view it in. Every well cut diamond will have sufficient fire in lighting which promotes its occurrence.''


or


''I relegate ''fire'' as a secondary attribute of beauty. Brilliance, Sparkle and Intensity (light Return, scintillation and contrast) are the PRIMARY measures of light behavior.''

I REALLY don''t agree.

Scintillation will only be nice if the fire is great.

I think he said that because there is no tool to measure fire.

Btw I do disagree and disagree with Dave on that statement.
When you think inside the box of new grade AGS0 RB he is mostly correct.
They will have enough fire to be beautiful.
When you get outside that box into other well cut, beautiful, high performance diamonds then it becomes an issue.

Also I feel scintillation can not be discussed or measured without considering fire vs white light vs surface contrast.
Scintillation really has 2 parts the diamonds appearance itself and the interaction with the surroundings. ie, light hitting things around it and becoming visible including the eye of the viewer.

 

[strmrdr]

Date: 8/29/2008 6:21:07 PM
Author: QueenMum
Do you see scintillation under other lighting than direct lighting?

Yes!
Moving contrast patterns are scintillation.

 

[strmrdr]

scintillation is defined as dynamic fire and dynamic contrast(including moving patterns and white light) when a diamond and/or light source and/or observer are moved.

If only fire was considered scintillation the princess cuts and radiants would have practically none which we know isn''t the case.

 

[Stephan]

Date: 8/29/2008 6:30:23 PM
Author: strmrdr

Date: 8/29/2008 6:21:07 PM
Author: QueenMum
Do you see scintillation under other lighting than direct lighting?

Yes!
Moving contrast patterns are scintillation.

I don''t think that way.
Moving contrast patterns can not be noticed in a bus under soft lighting by a person sitting 10 feet away from you.
I tend to call those moving contrasts something like "depth impression" of the diamond.
What I call a beautiful scintillation has to be fast and must be visible from a distance, so it won''t happen under soft lighting. What I call "scintillation" is visible under direct lighting, and to be beautiful, it has to be fast, with a lot of spots.
So for me, scintillation is the combination of a lot of strong fire spots that move fast and glare.
In GOG''s video, the stone on the left scintillates, the one on the right just has some fire.
But that is just because we have another definition for the word scintillation, so I don''t totally disagree with you.

 

[Stephan]

Date: 8/29/2008 6:40:16 PM
Author: strmrdr
If only fire was considered scintillation the princess cuts and radiants would have practically none which we know isn''t the case.

If you speak about fancy cuts, yes, princess cuts and radiants are just the ugliest to my eye, almost totally lack of fire/scintillation and are just cut for yield.

Emerald cuts produce, when well cut, what I call scintillation: dancing glare, and big flashes of fire jumping from a place to another.

 

[Garry H (Cut Nut)]

Date: 8/29/2008 5:46:00 PM
Author: QueenMum

Date: 8/29/2008 5:01:59 PM
Author: strmrdr
If 40.8 and 41 are both well matched to the crown with the same lgf% there is little if any visible difference going from one to the other.

But I think that 40.8 pavilion would be a better match for a 33.5 pavilion and that a 41 pavilion will be better with a 33 crown.
And if for you both pavilions are equal, then the 40.8 would be a better choice because of the spread.
I've once had a diamond with 59.5% depth, 58% table, 33.7 crown, 43% pavilion, stars +/- 60%, lgf about 80%, and it looked better than any H&A - AGS0 I saw, the fire was omnipresent.

The real problem is that I don't know any tool that can measure fire like the Idealscope measures light return.
Face-up views don't tell a lot about fire, fire should always be analyzed by tilting a diamond.
I have an Infinity, an EightStar; I had a New Line ACA and I saw Classic ACA's, all have a different type of fire, and some have (much) more.
Jonathan's videos are the best representation of differences in fire, and that's really not enough.
I think Dave Atlas wrote a long time ago on this forum something like: 'fire is not important when evaluating a diamond because it's not predictable', or something like that.
I really don't agree.
I do agree with Garry H. by preferring slightly shallow diamonds to the common H&A's, but then again I don't agree with him when he says that minor facets are not important.
I think most H&A's on the market are not bargains, because of the high price and the to big importance given to light return by steep/deep combo's (understand for example 34.8/40. that kill fire/scintillation.
Also remember, who thinks about diamonds thinks money: Brian once pointed out that by choosing a 40.7-40.8 pavilion (his preference), he was loosing I don't remember what yield percentage to obtain more beauty. But only one percent of BlueNile's yearly sale would make me happy.
So try to imagine how much money would be lost if the ideal combo becomes 33.5/40.8, long stars, long lgf's with a 56% table.

I prefer slightly shallower diamonds because I believe they are less affected by grease and dirty pavilions, and because the head obstruction (which is imprtant at buying time) is not a common problem during everyday wear.

I neve said minor facets were not important - I said many times when GIA was disproving all other grading systems were valid buy overemphasising minor facets - that this was bunkum. Of course minor facets are important, but the number of times you come across a stone with good T C and P - where there is a problem with minor facets is quite rare. It is obvious in most photo's and all ideal-scope / ASET's.

 

[Stephan]

Date: 8/28/2008 6:07:38 PM
Author: strmrdr

In Brian''s case it isn''t his main preference for his idea of visual balance which is why he picked a different combo for most of his goods.

We know to what angles 99% of the ACA''s are cut.
So, if I listen to you, that''s Brian main preference.
We also see that the 7.52ct is different (lower HCA score, shallower crown, longer stars, old AGS report, no Sarin, ...)
It would be interesting to know if his biggest ACA is outside his preference.
I loved this diamond (more than the common ACA, and not only for its disgusting size

).

 

[Stephan]

Date: 8/29/2008 6:58:04 PM
Author: Garry H (Cut Nut)
Of course minor facets are important, but the number of times you come across a stone with good T C and P - where there is a problem with minor facets is quite rare.

Yes but it happens, like the one I had re-cut because the lgf''s were much too long (for the crown/pavilion/table combo) and very very slightly painted, but enough to kill the fire in the diamond.

In other diamonds that are less extreme than this last one, lower and upper girdles can vary much more without making the diamond bad, but some minor facet combo''s are obviously better like I''ve seen in real life or when looking at GOG''s videos.

So even if I don''t agree with GIA by giving an excellent grade to some very steep/deep diamonds and knocking out many beautiful shallow diamonds, I appreciate the fact that they tried to analyze the "not so minor" facets regarding different table, pavilion and crown combinations.
I also appreciate their efforts to analyze painting and digging.

I still use the HCA, and Paulsen''s Diamond Cross-Section.

 

[Garry H (Cut Nut)]

Date: 8/29/2008 7:20:48 PM
Author: QueenMum

Date: 8/29/2008 6:58:04 PM
Author: Garry H (Cut Nut)
Of course minor facets are important, but the number of times you come across a stone with good T C and P - where there is a problem with minor facets is quite rare.

Yes but it happens, like the one I had re-cut because the lgf''s were much too long (for the crown/pavilion/table combo) and very very slightly painted, but enough to kill the fire in the diamond.

In other diamonds that are less extreme than this last one, lower and upper girdles can vary much more without making the diamond bad, but some minor facet combo''s are obviously better like I''ve seen in real life or when looking at GOG''s videos.

So even if I don''t agree with GIA by giving an excellent grade to some very steep/deep diamonds and knocking out many beautiful shallow diamonds, I appreciate the fact that they tried to analyze the ''not so minor'' facets regarding different table, pavilion and crown combinations.
I also appreciate their efforts to analyze painting and digging.

I still use the HCA, and Paulsen''s Diamond Cross-Section.

Stephan you are on shaky ground with a little knowledge and a lot of confidence.
Your diamond as it was had no minor facet problesm - it had a ghastly amount of painting top and bottom and if that and only that was fixed then you could have had a very fine shallow diamond with nothing of the weight loss you suffered.

Re GOG video''s - It is easily possible to film in the lighting Jon uses and make bad diamonds look better and good diamonds look worse simply by changing the angle relationship to the light / gem / camera. It is the very same reason that gIA ended up with a steep deep proportion set included into their Ex cut proportions.

 

[Stephan]

Date: 8/29/2008 7:44:49 PM
Author: Garry H (Cut Nut)
Stephan you are on shaky ground with a little knowledge and a lot of confidence.
Your diamond as it was had no minor facet problesm - it had a ghastly amount of painting top and bottom and if that and only that was fixed then you could have had a very fine shallow diamond with nothing of the weight loss you suffered.

Hey Jim, that's not very nice, is it?
In Belgium, people would say you are rude.
You should have more patience with someone who made the effort to write in a language that isn't his mother tongue.
My mother tongue is German, I went to school in French, speak Dutch at work and Vietnamese at home so please excuse my bad English.

Garry, with all the respect from a poor and stupid boy like me do have for you and your unmatched and incommensurable erudition, please notice that the upper girdle of the diamond wasn't painted, ONLY the pavilion as I've already told you in the other thread.
I've had a lot of diamonds before owning some unbranded H&A's (Muller & Son), 3 Infinity's, 1 ACA and 1 EightStar. And believe it or not, I can use a loupe to look at a girdle.

We are on a shaky ground, we all agree.
But then you could try to being constructive and pointing out where I'm wrong, I'm sure you can do that with your encyclopedic knowledge.
That way, you wouldn't need to express a judgment on my knowledge, you would prove by A+B that I'm just a fool, and with much more elegance.
It's not my fault if your subordinates didn't implement the minor facets in your HCA script but it isn't a reason to become fractious every time somebody dares to raise the issue.

PS: Aren't you on a shaky ground with your HCA when, on a YouTube video with Brian, you have to admit that some "only" very good diamonds on the HCA (score>2) still are excellent if they have a perfect symmetry?
I do not even imagine what kind of pressure you have endured...

 

[Garry H (Cut Nut)]

Date: 8/29/2008 8:36:39 PM
Author: QueenMum

Date: 8/29/2008 7:44:49 PM
Author: Garry H (Cut Nut)
Stephan you are on shaky ground with a little knowledge and a lot of confidence.
Your diamond as it was had no minor facet problesm - it had a ghastly amount of painting top and bottom and if that and only that was fixed then you could have had a very fine shallow diamond with nothing of the weight loss you suffered.

Hey Jim, that''s not very nice, is it?
In Belgium, people would say you are rude.
You should have more patience with someone who made the effort to write in a language that isn''t his mother tongue.
My mother tongue is German, I went to school in French, speak Dutch at work and Vietnamese at home so please excuse my bad English.

Garry, with all the respect from a poor and stupid boy like me do have for you and your unmatched and incommensurable erudition, please notice that the upper girdle of the diamond wasn''t painted, ONLY the pavilion as I''ve already told you in the other thread.
I''ve had a lot of diamonds before owning some unbranded H&A''s (Muller & Son), 3 Infinity''s, 1 ACA and 1 EightStar. And believe it or not, I can use a loupe to look at a girdle.

We are on a shaky ground, we all agree.
But then you could try to being constructive and pointing out where I''m wrong, I''m sure you can do that with your encyclopedic knowledge.
That way, you wouldn''t need to express a judgment on my knowledge, you would prove by A+B that I''m just a fool, and with much more elegance.
It''s not my fault if your subordinates didn''t implement the minor facets in your HCA script but it isn''t a reason to become fractious every time somebody dares to raise the issue.

PS: Aren''t you on a shaky ground with your HCA when, on a YouTube video with Brian, you have to admit that some ''only'' very good diamonds on the HCA (score>2) still are excellent if they have a perfect symmetry?
I do not even imagine what kind of pressure you have endured...

Dear Stephan,
I am sorry that I did indeed feel it would help you if I was rude. I was deliberately so because you are - in my opinion - at risk.
I need not be right, but I feel I am.

You are probably right that the painiting was only on the pavilion side (which is worse than crown side on a shallow stone.).

Your stone as it was could possibly have had the pavilion painting removed with hardly any weight loss. This would have made it a much nicer looking stone.

I would prefer you do not missquote me.
My HCA patent covers minor facets - it was not something I was unaware of, I also knew at the time about painting and knew and kept 8*''s trade secret for many years. I had no underlings work on the raw HCA data.

I do not endure any pressure.

 

[strmrdr]

QueenMum,

While I try not to be a blunt as my friend Garry he has a point.

I am willing to explore your personal preference with you as long as you don''t mind it being pointed out that is what it is and on the grounds that no one else''s preferences or diamonds are bad mouthed.
Several experts are already scared off from this thread as it as it headed down a road no one wants to go and can hurt feelings for no good reason.

There are many combinations that make beautiful diamonds and many different opinions on just what it is that makes a diamond beautiful I am willing to explore yours with you.
I did not realize just how many combinations can produce beautiful diamonds until I started designing them.

 

[strmrdr]

Date: 8/29/2008 6:27:32 PM
Author: strmrdr
This should read:

Btw I do agree and disagree with Dave on that statement.

When you think inside the box of new grade AGS0 RB he is mostly correct.

They will have enough fire to be beautiful.

When you get outside that box into other well cut, beautiful, high performance diamonds then it becomes an issue.


Also I feel scintillation can not be discussed or measured without considering fire vs white light vs surface contrast.

Scintillation really has 2 parts the diamonds appearance itself and the interaction with the surroundings. ie, light hitting things around it and becoming visible including the eye of the viewer.

 

[strmrdr]

Date: 8/29/2008 6:48:08 AM
Author: DiaGem

Date: 8/28/2008 6:48:00 PM

Author: strmrdr

disclaimer: the stars are usually cut last so long stars are the effect of steeper upper girdles.


But when designing and thinking about the effect on the crown it is easier to think of the longer stars as the cause of the steeper uppers.

Actually..., based on my knowledge and experience..., the star facets are the first stage of the brillianteering!

And you can control the upper halves angles based on the amount of digging you are planning into the girdle plane...

DiaGem I looked into this and we are both right.
Depending on where and by who and somewhat on the size of the stone the order of cutting the facets differ.
The person I was quoting was talking about many common fine make lines.
A melee line may be ran different and some places where one person does the entire crown it may be done differently depending on which person there is doing the polishing.
Anyway the end result is the same in regard to the stars and the upper girdles when cut to a classic profile.

 

[Stephan]

Date: 8/29/2008 10:53:05 PM
Author: Garry H (Cut Nut)
Dear Stephan,

I am sorry that I did indeed feel it would help you if I was rude. I was deliberately so because you are - in my opinion - at risk.
I need not be right, but I feel I am.

I''m sorry too.

You are probably right that the painiting was only on the pavilion side (which is worse than crown side on a shallow stone.).

Your stone as it was could possibly have had the pavilion painting removed with hardly any weight loss. This would have made it a much nicer looking stone.

I would prefer you do not missquote me.
My HCA patent covers minor facets - it was not something I was unaware of, I also knew at the time about painting and knew and kept 8*''s trade secret for many years. I had no underlings work on the raw HCA data.

I didn''t write about your patent, but about the HCA.
And the only minor facets you can introduce in the cut adviser are the culet and the girdle (by deduction).

 

[Stephan]

Date: 8/30/2008 1:09:13 AM
Author: strmrdr
I am willing to explore your personal preference with you as long as you don''t mind it being pointed out that is what it is and on the grounds that no one else''s preferences or diamonds are bad mouthed.

I agree with you, I''ve just another definition of fire and scintillation than you.

- Scintillation in soft lighting is something unseen by me, even with my ACA, my EightStar or other Infinity''s. I call that everything you want, but not scintillation, that in its French definition is really something different from "moving contrast patterns". I think Pricescope''s definition of scintillation is the same than yours, but I just can''t agree.

- Dispersion under soft lighting do exist, but do you think I''m wrong by saying that it isn''t a big deal, and that it won''t catch anyone''s eye when observed from more than 10 feet under soft lighting?

Several experts are already scared off from this thread as it as it headed down a road no one wants to go and can hurt feelings for no good reason.

Experts make money with the feelings of the consumer (=> me for example).
So sorry if I don''t care about their feelings.
Nobody is bad mouthed here, and if someone feels like that, he has the opportunity to defend himself.
We are here on a forum, a place to discuss.

I started this topic to talk about fire under direct lighting.
Can any expert answer to the following question:
With what pavilion and lgf a diamond will have the most fire under direct lighting when the crown is 34, table 55 and star 65 (just for example)?

A lot of you would answer "a lot of possibilities".

Even if I have no knowledge as Garry pointed out, I still have my eyes.
And the experience of my eyes tell me that perfect light return (=> perfect Idealscope) is much easier to obtain than perfect fire under direct lighting (just see all the diamonds sold as ideal and all the different C/P combo''s that still have nice Idealscopes).

Perhaps am I the only one thinking like that on this forum but, strange enough, my friends, colleagues and family think like me and they all compare the diamonds I had under direct lighting.

 

[Garry H (Cut Nut)]

Date: 8/30/2008 5:06:11 AM
Author: QueenMum

Date: 8/29/2008 10:53:05 PM
Author: Garry H (Cut Nut)
Dear Stephan,

I am sorry that I did indeed feel it would help you if I was rude. I was deliberately so because you are - in my opinion - at risk.
I need not be right, but I feel I am.

I''m sorry too. Did you learn anything? (if I hurt you and there was no benefit then as a human I apologise)

You are probably right that the painiting was only on the pavilion side (which is worse than crown side on a shallow stone.).

Your stone as it was could possibly have had the pavilion painting removed with hardly any weight loss. This would have made it a much nicer looking stone.

I would prefer you do not missquote me.
My HCA patent covers minor facets - it was not something I was unaware of, I also knew at the time about painting and knew and kept 8*''s trade secret for many years. I had no underlings work on the raw HCA data.

I didn''t write about your patent, but about the HCA.
And the only minor facets you can introduce in the cut adviser are the culet and the girdle (by deduction). HCA has cost me approaching $100k and has made me $0. GIA are technically in breach of my patent. I no longer believe it is a ''cut grade'' system - it should only be used for rejection. Minor facets or applying it to any other cuts is an exponential jump in development and implimentation costs.
What do you (the collective you) want of me?

 

[Stephan]

Date: 8/30/2008 6:01:41 AM
Author: Garry H (Cut Nut)
Minor facets or applying it to any other cuts is an exponential jump in development and implimentation costs.

Of course, and GIA's system was probably more expensive than yours and not as good as yours.

What do you (the collective you) want of me?

Thanks Garry, you made my day.

My questions are above (and below again):

If you know that the most interesting thing for me in a diamond is fire and scintillation under direct light, then:
1) What are the perfect pavilion and lgf for a 34 crown 55 table 65 star?
(I'm so precise because I know otherwise there would be too much answers.)
2) Do you think I'm true that perfect fire under direct lighting is more difficult to obtain than a nice Idealscope?

Thank you!

 

[Garry H (Cut Nut)]

Date: 8/30/2008 6:14:17 AM
Author: QueenMum

Date: 8/30/2008 6:01:41 AM
Author: Garry H (Cut Nut)
Minor facets or applying it to any other cuts is an exponential jump in development and implimentation costs.

Of course, and GIA''s system was probably more expensive than yours and not as good as yours.

What do you (the collective you) want of me?

Thanks Garry, you made my day.

My questions are above (and below again):

If you know that the most interesting thing for me in a diamond is fire and scintillation under direct light, then:
1) What are the perfect pavilion and lgf for a 34 crown 55 table 65 star?
(I''m so precise because I know otherwise there would be too much answers.)
2) Do you think I''m true that perfect fire under direct lighting is more difficult to obtain than a nice Idealscope?

Thank you!

I have no good idea what "direct lighting" is. I know it is a term bandied about here, but you have never heard me use it, and to my knowledge there is no definition of it because no one has ever defined it.

GIA''s system is my system from a patent point of view. It is system to use look up charts. I did mine, GIA did theirs. You can do your own charts, you can even use AGS''s if you want and make your own princess cut version.

 

[Stephan]

Date: 8/30/2008 7:14:42 AM
Author: Garry H (Cut Nut)
I have no good idea what "direct lighting" is.

By direct lighting, I mean halogen lamps or every lighting similar to GIA''s Diamond Dock LED lighting you used for this video.

 

[Gizmo150808]

I need help i bought two stud earrings H&A GIA #16509049 and #16462919 but i heard gia don''t grade Heart and Arrow diamond but i my report it says "ADDITIONAL INSCRIPTION H&A" what does this mean

 

[Garry H (Cut Nut)]

Date: 8/30/2008 7:47:59 AM
Author: QueenMum

Date: 8/30/2008 7:14:42 AM
Author: Garry H (Cut Nut)
I have no good idea what ''direct lighting'' is.

By direct lighting, I mean halogen lamps or every lighting similar to GIA''s Diamond Dock LED lighting you used for this video.

Halogen lights are usually in the ceiling, say 2 Meters above the diamond. The halogen lamp is typically 51mm diameter. That is about an angle of 1.4 degrees from one side of the light source to the other. How many halogens make up a ''direct light'' source? What colour and tone are the walls? Is there any other ambient light? What is the background? What is the angle of the lights / diamond / observer to each eye? Halogen is red intense and less blue wavelengths.

The 12 GIA LEDs have an angle of less than 1 degree, but there is a lot more of them in a close area than any room i have seen other than jewellers in hong Kong. They are cold blue with little red I think. We know the background is very bright, which makes the diamond body appear very dark because of our eyes accomodation to the background, therefore we will indeed see mainly the bright flashes. There is little ambiant light effect unless you are in a very bright room.

If you can tell me what direct lighting should be then it will help me because lighting for daimond analysis is a critical task I am working on right now Stephan.

You are good with a camera - set on auto and try looking at exposure times in various lighting conditions where you can see the best attributes for ''direct lighting'' where you can most easily discern these features. See what happens when you look or photograph on white vs dark backgrounds.
When you find an optimal environmet please take fish eye photo''s with various exposures - for the lights only, and the walls and ceilings only etc.

I can use them to model your ''direct lighting'' in DiamCalc in HRDI format and answer your question.

 

[Garry H (Cut Nut)]

Date: 8/30/2008 8:09:18 AM
Author: Gizmo150808
I need help i bought two stud earrings H&A GIA #16509049 and #16462919 but i heard gia don''t grade Heart and Arrow diamond but i my report it says ''ADDITIONAL INSCRIPTION H&A'' what does this mean

Gizmo you are posting in the wrong place. Post on the normal board - not inside a thread.
It means GIA record what is written on the stone. Many times we find such diamonds have lousy H&A''s

 

[Stephan]

You are right Garry, direct lighting is a too vast notion.
I like Jonathan''s lighting when he shows the fire in his videos.
I use to compare diamonds in a dark room next to the bathroom by looking at the mirror in the bathroom from the dark and a 10-13 feet distance with only two lamps (not halogen) above the mirror.
It shows me not only the fire, but the power of fire (some nice fire sometimes won''t go far) and the "speed" of the scintillation.