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FIC vs TIC: what is the light performance difference-style?

dumbo

Shiny_Rock
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Jan 5, 2015
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Just a random question: I couldn't really find it answered elsewhere: the diamond I purchased is a 1.4 FIC on the HCA scale:

62.4 depth %
55.5 table %
35.6 Crown angle
40.6 Pavilion angle

I assume those are "desirable" angles?

How does this differ in performance from a more typical sub 2 TIC on the HCA scale? More fire I take it, but at the expense of what? Overall brightness? And what kind of percentages are we talking: 5 percent more fire, 5 percent less brightness? Obvious, or subtle differences? I was only able to compare it to the Hearts on Fire diamonds, which didn't have published angles. When a diamond is cut, is there a reason it is cut with a bit larger Crown Angle that gives it an FIC rating? Does it depend on the diamond, the preference of the cutter, or is just random variance? Does one style carry a price premium or discount, or are they considered similar in quality? Just curious, thank you!

If it matters, here is the cert:

http://www.agslab.com/pdf_sync_reports/104069729011-PLDQR.PDF
 

Paul-Antwerp

Ideal_Rock
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Re: FIC vs TIC: what is the light performance difference-sty

dumbo|1427088980|3851203 said:
How does this differ in performance from a more typical sub 2 TIC on the HCA scale? More fire I take it, but at the expense of what? Overall brightness? And what kind of percentages are we talking: 5 percent more fire, 5 percent less brightness? Obvious, or subtle differences?
Hi Dumbo,

I find the detailing of HCA into TIC, FIC and BIC a confusing generalisation. It is based upon the age-old thinking that a higher and steeper crown increases the dispersion of a diamond. While true in a situation of all-other-aspects-equal, there are far better ways to increase the perceived Fire from a diamond. Therefore, at best, I find this terminology confusing.

dumbo|1427088980|3851203 said:
When a diamond is cut, is there a reason it is cut with a bit larger Crown Angle that gives it an FIC rating? Does it depend on the diamond, the preference of the cutter, or is just random variance? Does one style carry a price premium or discount, or are they considered similar in quality? Just curious, thank you!
Obviously, it is impossible to know the motives of a specific cutter, but the average extra weight-retention of about 4% for the same diameter is probably a potential motivator.

Live long,
 

tyty333

Super_Ideal_Rock
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Re: FIC vs TIC: what is the light performance difference-sty

Can you get an idealscope image or an aset image of the stone? You can compare those with a well cut TIC stone and see what
differences there might be.
 

dumbo

Shiny_Rock
Premium
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Messages
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Re: FIC vs TIC: what is the light performance difference-sty

tyty333|1427116179|3851247 said:
Can you get an idealscope image or an aset image of the stone? You can compare those with a well cut TIC stone and see what
differences there might be.
600_172782-aset_black__fancy_-01.jpg

here it is. Looks pretty bright under the crown.

600_172782-idealscope-01.jpg
 

ecf8503

Ideal_Rock
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3,706
Re: FIC vs TIC: what is the light performance difference-sty

I'd be more concerned about whether it's eye clean or not...
 

dumbo

Shiny_Rock
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Re: FIC vs TIC: what is the light performance difference-sty

It is, it looks great!
 

tyty333

Super_Ideal_Rock
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Re: FIC vs TIC: what is the light performance difference-sty

Sort of reminds me of this stone with a higher than usual crown.
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3253498.htm

The aset and idealscope both look good and dont look far off when compared to TIC stones. ( I compared it with some whiteflash
ACA stones.)

Well, here is my* opinion...because it has Ideal Light Return (AGS), I don't think the high crown is affecting the light return.
If it were for me, this would be acceptable.

I do worry about the inclusions though. Have you had it verified as eye-clean to your standards?

Do you have a real picture of the stone?
 

dumbo

Shiny_Rock
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Re: FIC vs TIC: what is the light performance difference-sty

tyty333|1427199545|3851704 said:
Sort of reminds me of this stone with a higher than usual crown.
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3253498.htm

The aset and idealscope both look good and dont look far off when compared to TIC stones. ( I compared it with some whiteflash
ACA stones.)

Well, here is my* opinion...because it has Ideal Light Return (AGS), I don't think the high crown is affecting the light return.
If it were for me, this would be acceptable.

I do worry about the inclusions though. Have you had it verified as eye-clean to your standards?

Do you have a real picture of the stone?
Eye clean to me! I can't see an inclusion unless I know where and how to look (at what angle), and I have better than 20/20 eyesight.

Sorry for the poor pics: I loaned my macro lens to a friend.

Back to the FIC vs TIC: what would I see vs a diamond with a lower 34.9 crown angle, that is more typical of a "normal" whiteflash diamond?


img_3479_0.jpg
img_3472.jpg
 
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al_g

Rough_Rock
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Dec 4, 2019
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Back to the FIC vs TIC: what would I see vs a diamond with a lower 34.9 crown angle, that is more typical of a "normal" whiteflash diamond?
I'm wondering about this too. I'm considering a diamond with a steeper crown angle as well.
 
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TODiamonds

Shiny_Rock
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Jul 27, 2019
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260
Angles are perfectly fine. They are complementary and the stone looks great from your pics. Don't overthink it or get trapped into thinking you need a 34.5/40.8.

As others have said I'd be concerned about those inclusions, but I'm assuming you've already checked that box.
 

OoohShiny

Ideal_Rock
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6,693
As others have said I'd be concerned about those inclusions, but I'm assuming you've already checked that box.
I would hope so in the four years since this thread was started ;-) :lol:
 

AV_

Ideal_Rock
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Aug 5, 2018
Messages
2,908
These are very slight variations & not easy to describe at all. The stones would make a perfectly matched pair, out of which you could still identify each twin not in any one position but by watching how light plays off facets as you turn them slightly; the effect is minute ...
 

Garry H (Cut Nut)

Super_Ideal_Rock
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You would expect to see a tiny bit more fire, and a tiny bit less brightness. There can be some more darkness (= less brightness) which should show up as more small dark to bright flashes especially around the outer edges because the steeper crown directs more light from the table into the crown facets.
The price is usually a little less because the spread is a little smaller (HCA can give a guide on that).
 
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