Technical Questions on Round Brilliant Cuts

[tarssarb]

I have a few residual diamond questions from my reading of this site.

1) How similar are the concepts of fire as in FIC and fire on a gemex brilliancescope report. It seems that most heart and arrow TIC cuts max out the fire on the Gemex report, whereas the tutorial discusses how fire is best seen with diamonds with lower light return. Further, this thread discusses the transition of a diamond from a prism to mirror: https://www.pricescope.com/community/threads/which-would-you-choose.15402/page-2

Does this mean a FIC will demonstrate fire further into a diffuse lighting environment than a TIC/BIC?
Further does the pricescope use of the word fire best refer not to a nominal output level of color but rather to a ratio of color to white light?

2) Does anyone have the total percent light return graph along the Octonus-MSU ideal line?

3) Roughly what minimum carat size is necessary in an ideal cut stone to easily see differences between BIC and FIC stones (not up close character differences, 3 feet viewing differences) in direct and/or diffuse light given that ideal cuts will typically all have high levels of light returns.

4) Is it fairly accurate to summarize that for the most part the only real differences of an ideal H&A stone are personality type differences upon close viewing given by the lgf and star girdle sizes?

5) Finally, it seems like the only easily accessible data for ideal cut stones is the table size. From the tutorial, larger tables are brighter but have less fire. I have seen Gemex 57%tables with pegged color return and 54-55% reports with sub optimal color return. In real life, how much does the table affect the fire/dispersion compared to the pavillion/crown angles?

Thanks!

 

[strmrdr]

Date: 2/23/2006 4:39:12 PM
Author:tarssarb
I have a few residual diamond questions from my reading of this site.

ahh someone after my own heart.
tough questions Ill take a shot at it :}


1) How similar are the concepts of fire as in FIC and fire on a gemex brilliancescope report. It seems that most heart and arrow TIC cuts max out the fire on the Gemex report, whereas the tutorial discusses how fire is best seen with diamonds with lower light return. Further, this thread discusses the transition of a diamond from a prism to mirror: https://www.pricescope.com/community/threads/which-would-you-choose.15402/page-2

There is a certain folly in seprating out colored from white light.
White light is made up of colored light so the light still shows up after filtering as colored light.
Thus diamonds with the highest level of light return can score tripple vh even if they are tuned to white light return.

The most fiery diamonds do have reduced white light return.
The simple reason is that there is a max amount of light that can be returned and one may break it up into colors and one not but it cant return it both ways.







Does this mean a FIC will demonstrate fire further into a diffuse lighting environment than a TIC/BIC?

in genersal yes, but in some lighting no diamond will have fire

Further does the pricescope use of the word fire best refer not to a nominal output level of color but rather to a ratio of color to white light?

fire is colored light return, white light masks fire so if your seeing fire the fire isnt being masked so there by defintion is a higher ratio of colored to white light. This is an area id like to explore because our eyes can reach saturation where a very bright colored light can look white im curious if a lesser strength white light can mask a stronger colored light source


2) Does anyone have the total percent light return graph along the Octonus-MSU ideal line?

there is one around here some place i think


3) Roughly what minimum carat size is necessary in an ideal cut stone to easily see differences between BIC and FIC stones (not up close character differences, 3 feet viewing differences) in direct and/or diffuse light given that ideal cuts will typically all have high levels of light returns.

difference in cut in my .15 h&a compared to other diamonds are apparent but not sure about at 3 feet. 1/2ct id say for sure at 3 feet the differences would be apparent


4) Is it fairly accurate to summarize that for the most part the only real differences of an ideal H&A stone are personality type differences upon close viewing given by the lgf and star girdle sizes?

no the crown and pavilion angles make the bigger difference, followed by lgf% followed by painting of the upper girdles followed by star %


5) Finally, it seems like the only easily accessible data for ideal cut stones is the table size. From the tutorial, larger tables are brighter but have less fire. I have seen Gemex 57%tables with pegged color return and 54-55% reports with sub optimal color return. In real life, how much does the table affect the fire/dispersion compared to the pavilion/crown angles?

the table size is lower on the list than a lot of variables in light return but high on the list in appearance when it gets to extremes.
For practical purposes with most crown/pavilion angles a change from 54 to 57 will have little effect.

Thanks!

thanks for taking my mind off my tooth :}

 

[belle]

Date: 2/23/2006 4:39:12 PM
Author:tarssarb
I have a few residual diamond questions from my reading of this site.

1) How similar are the concepts of fire as in FIC and fire on a gemex brilliancescope report. It seems that most heart and arrow TIC cuts max out the fire on the Gemex report, whereas the tutorial discusses how fire is best seen with diamonds with lower light return. Further, this thread discusses the transition of a diamond from a prism to mirror: https://www.pricescope.com/community/threads/which-would-you-choose.15402/page-2

not really similar at all being that one of them relies solely on accuracy of measurements put in by the user and the other ''measures'' and gives results based on the pre-programmed metrics.

Date: 2/23/2006 4:39:12 PM
Author:tarssarb

Does this mean a FIC will demonstrate fire further into a diffuse lighting environment than a TIC/BIC?

you may notice more flashes of color in low light conditions with a fic than a bic or maybe a tic

Date: 2/23/2006 4:39:12 PM
Author:tarssarb

Further does the pricescope use of the word fire best refer not to a nominal output level of color but rather to a ratio of color to white light?

as far as i know, there is no definition from the ''pricescope'' use of the word fire. to me, fire is the abundance of color radiating from within a diamond as opposed to bright (white) flashes of sparkle.

Date: 2/23/2006 4:39:12 PM
Author:tarssarb

2) Does anyone have the total percent light return graph along the Octonus-MSU ideal line?

that might take some digging.

Date: 2/23/2006 4:39:12 PM
Author:tarssarb

3) Roughly what minimum carat size is necessary in an ideal cut stone to easily see differences between BIC and FIC stones (not up close character differences, 3 feet viewing differences) in direct and/or diffuse light given that ideal cuts will typically all have high levels of light returns.

some people can''t notice the difference in any size at any difference. it really depends on the viewer.

Date: 2/23/2006 4:39:12 PM
Author:tarssarb

4) Is it fairly accurate to summarize that for the most part the only real differences of an ideal H&A stone are personality type differences upon close viewing given by the lgf and star girdle sizes?

not at all. the crown/pavilioin angle relationship plays a huge role. lgf do play a big part, as do the other factors. you have to look at the whole picture.

Date: 2/23/2006 4:39:12 PM
Author:tarssarb

5) Finally, it seems like the only easily accessible data for ideal cut stones is the table size. From the tutorial, larger tables are brighter but have less fire. I have seen Gemex 57%tables with pegged color return and 54-55% reports with sub optimal color return. In real life, how much does the table affect the fire/dispersion compared to the pavillion/crown angles?

again, it''s not just one factor that plays a role. it is everything working together. i wouldn''t make any scientific judgements based on a gemex report. just like other devices, it is limited to the metrics programmed by the designer.

 

[belle]

hahahha...hi strm

(off to check your answers)

 

[tarssarb]

On the minimum size, I mean for two ideal hearts and arrows with one falling with a BIC (say 33.5/41) and the other at a FIC (say 35/40.6). My experience looking around is that pretty much all heart and arrows ideals fall in this range. Thus, the questions: can you noticeably see fire and brightness differences between these extremes (and at what size) and if not is the only remaining practical variable the LGF% (the spikiness/personality of the arrows). My limited experience was that the tables changes from 55-57 did little to the overal character of the stone.

Thanks again!

 

[strmrdr]

Date: 2/23/2006 6:01:06 PM
Author: tarssarb
On the minimum size, I mean for two ideal hearts and arrows with one falling with a BIC (say 33.5/41) and the other at a FIC (say 35/40.6). My experience looking around is that pretty much all heart and arrows ideals fall in this range. Thus, the questions: can you noticeably see fire and brightness differences between these extremes (and at what size) and if not is the only remaining practical variable the LGF% (the spikiness/personality of the arrows). My limited experience was that the tables changes from 55-57 did little to the overal character of the stone.


Thanks again!

Yes you would see the difference.
depending on distance and eyesight and how your brain is wired and the biggest variable would be lighting id say someplace between .15 and .5 the difference would become visible to most people.

The LGF needs to be balanced with the others facets when you hit the extremes, low lgf% does not work well with fics at all, and bics are generaly better in the short to mid range.
Long lgf% bics can have too little contrast so the lgf% needs to be shorter to pick up some contrast.
Short lgf% fics give up too much brightness.

It is a complicated balancing game when it comes to diamond design.

 

[belle]

Date: 2/23/2006 6:01:06 PM
Author: tarssarb
On the minimum size, I mean for two ideal hearts and arrows with one falling with a BIC (say 33.5/41) and the other at a FIC (say 35/40.6). My experience looking around is that pretty much all heart and arrows ideals fall in this range. Thus, the questions: can you noticeably see fire and brightness differences between these extremes (and at what size) and if not is the only remaining practical variable the LGF% (the spikiness/personality of the arrows). My limited experience was that the tables changes from 55-57 did little to the overal character of the stone.

Thanks again!

again, i defer to my statement above. however vague and unscientific it may seem..it totally depends on the viewer. and you can add into that the many variables of environment. there is absolutely no set answer for your question.

how about you find some bic''s and fic''s and then we can compare.

 

[strmrdr]

Date: 2/23/2006 6:28:57 PM
Author: belle

Date: 2/23/2006 6:01:06 PM
it totally depends on the viewer. and you can add into that the many variables of environment. there is absolutely no set answer for your question.

Agree with belle when it comes to what people see there is a lot of difference person to person which is one of the hard things for me to accept.
I want absolutes and there are very few of them when it comes to diamond looks and preferences.
It drives me nutz lol