Experts opinions needed - Is this a yield issue?

[Garry H (Cut Nut)]

Thanks - I left that out - the distance to observer has a big implication. You can see that on my video - as I back away the bright flashes turn to firey ones and fire gets more obvious.
Of course from what I know of Jonathons filming techniques, it is not the same as humans see. Every part of the process needs to be considered. Pupil size / camera aperature etc etc

 

[diagem]

Date: 8/30/2008 1:19:04 AM
Author: 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.

Strmrd..., I know there are multiple orders in the last stage of brillianteering...
But cutting the star facets first help cutters keep a symmetry balance...

A star facet is a facet that starts and finishes in one shot (usually no fine-tuning).
To cut upper halves you depend on a pair for symmetry! You dont cut the right ugf and then the other..., the position of the ugf''s are dependant on each other... (hope I am making sense....)

 

[strmrdr]

Date: 8/30/2008 5:57:24 AM
Author: QueenMum

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.

1: we cant change the definition of scintillation to suit your personal preference,,, sorry.
Yes white sparkle can catch someones eye 10 feet away.

2: fire under direct light is easy, even very badly cut diamonds will have it.
It is the easiest thing to achieve.
That is why jewelery stores have lots of it.

3: 41P 80%lgf is likely the best balance of virtual facets for that combo.

 

[strmrdr]

Garry this will help.
In optics class and photography direct light is defined as:
"direct lighting - light travels straight toward an object or surface that produces sharp shadows. Direct lighting light travels straight toward an object or surface that produces sharp shadows."

http://www.scs.sk.ca/cyber/elem/learningcommunity/sciences/physics20/curr_content/physics20/light/lightterms.htm

 

[strmrdr]

here is direct lighting in the bathroom.

 

[isaku5]

Date: 8/30/2008 10:35:16 AM
Author: strmrdr
here is direct lighting in the bathroom.

Hey! That''s a really lovely bathroom.....Are we going to see diamonds in that room?

 

[strmrdr]

This light bar above the mirror or one on each side and sometimes even on 3 sides that really makes diamonds pop

http://www.amazon.com/Sea-Gull-Lighting-Stainless-4739-98/dp/B000W0KCT2/ref=sr_1_6?ie=UTF8&s=furniture&qid=1220107336&sr=1-6

It would be a good light source to model as direct lighting as it is very very common in the US

This is also an example of the lighting that is being banned in the US.
It will be replaced by much softer cft or florescent tube lighting.

 

[strmrdr]

Another example of direct lighting in the home.
Also banned and to be replaced by cft lighting.

Recessed and track lighting.

http://www.junolighting.com/brand_juno.asp

 

[strmrdr]

this is how it is often used in the kitchen:

 

[strmrdr]

here is another example of direct lighting in the home which is also going away.....

 

[strmrdr]

another common bathroom light with direct light over the sink and softer light to the room.

Again being replaced by much softer cft lighting under new laws.

 

[strmrdr]

Another kitchen.
Notice the hard and distinct shadows.
Again this lighting is going away :{

 

[strmrdr]

another lighting source that would be good to model it is on a 8 foot high ceiling so figure 4-5 feet above a diamond for a 5 foot tall Woman.
Again this is not going to be used in new construction due to the new laws.

 

[Stephan]

Date: 8/30/2008 10:27:09 AM
Author: strmrdr
1: we cant change the definition of scintillation to suit your personal preference,,, sorry.
Yes white sparkle can catch someones eye 10 feet away.
41P 80%lgf is likely the best balance of virtual facets for that combo.

Here are some definitions of "scintillation" on the web.
http://en.wiktionary.org/wiki/scintillation
http://www.thefreedictionary.com/scintillation
I don''t think that my perception of scintillation deviates a lot from the origin, but your "moving contrast patterns" seems far from the origin for me. In French, it''s even more obvious. I don''t change any definition here.

2: fire under direct light is easy, even very badly cut diamonds will have it.
It is the easiest thing to achieve.
That is why jewelery stores have lots of it.

It''s easy to obtain, but it''s difficult to obtain it on a big number of facets at the same time, and difficult to find diamonds that will blind you with fire from a 12 feet distance while keeping a good light return.

41P 80%lgf is likely the best balance of virtual facets for that combo.

You make a point here if you post pictures (virtual facets and ASET) of:
1) 55% T 34 C 65% star --- 40.8 P 80% lgf
against
2) 55% T 34 C 65% star --- 41.0 P 80% lgf
I''m like Thomas...

 

[strmrdr]

This is what is replacing another source of direct light in the home.
The range hood.
Mine makes diamonds pop this one will not.

 

[strmrdr]

Date: 8/30/2008 11:15:40 AM
Author: QueenMum

You make a point here if you post pictures (virtual facets and ASET) of:

1) 55% T 34 C 65% star --- 40.8 P 80% lgf

against

2) 55% T 34 C 65% star --- 41.0 P 80% lgf

How about fire in pinpoint lighting instead....

Edit: to give credit this was inspired by Marty's lighting but is no where near as many light sources as he uses in his patented viewing device.

 

[Stephan]

How nice is that!
Honestly, I would have a hard time to choose!

 

[strmrdr]

Date: 8/30/2008 11:15:40 AM
Author: QueenMum

Date: 8/30/2008 10:27:09 AM

Author: strmrdr

1: we cant change the definition of scintillation to suit your personal preference,,, sorry.

Yes white sparkle can catch someones eye 10 feet away.

41P 80%lgf is likely the best balance of virtual facets for that combo.

Here are some definitions of ''scintillation'' on the web.

http://en.wiktionary.org/wiki/scintillation

http://www.thefreedictionary.com/scintillation

twinkling star is moving contrast patterns it certainly isn''t fire.
A princess cut under small movement meets that definition better than an 8*

 

[Stephan]

The one on the left looks brighter and bigger, the one on the right has some interesting colors like more red.

 

[Stephan]

Date: 8/30/2008 11:35:04 AM
Author: strmrdr
A princess cut under small movement meets that definition better than an 8*

Yes, from arm length distance...
Which picture above do you prefer?

 

[strmrdr]

Date: 8/30/2008 11:35:11 AM
Author: QueenMum
The one on the left looks brighter and bigger, the one on the right has some interesting colors like more red.

That will vary if the diamond is rotated.
This is with the "diamond" rotated 5 degrees from the image above.
Which one is it of the above combos is this?

 

[strmrdr]

Date: 8/30/2008 11:39:15 AM
Author: QueenMum

Date: 8/30/2008 11:35:04 AM

Author: strmrdr

A princess cut under small movement meets that definition better than an 8*

Yes, from arm length distance...

Which picture above do you prefer?

one out of 1000000 of the people on earth might be able to tell the difference between them in direct lighting if that many.
Direct lighting makes similar diamonds look alike more like each other than soft light.

 

[Stephan]

I love that kind of games!
I guess it''s the 40.8 because the reflection of the table at the culet looks bigger, but without conviction.

 

[strmrdr]

Which off these do you like better?

 

[strmrdr]

Date: 8/30/2008 11:46:47 AM
Author: QueenMum
I love that kind of games!

I guess it''s the 40.8 because the reflection of the table at the culet looks bigger, but without conviction.

41

 

[Stephan]

The left one, without hesitating.

 

[Stephan]

Is it deep?

 

[strmrdr]

Date: 8/30/2008 11:52:43 AM
Author: QueenMum
The left one, without hesitating.

You just feel for the jewelery store lighting trick!

 

[Stephan]

That''s why I go shopping with an idealscope.

Date: 8/30/2008 11:15:40 AM
Author: QueenMum
It''s easy to obtain, but it''s difficult to obtain it on a big number of facets at the same time, and difficult to find diamonds that will blind you with fire from a 12 feet distance while keeping a good light return.

 

[strmrdr]

which one of these?
They have the same pavilion.