Crown Angles & Fire

[just_looking!]

I''m sure that this has been answered somewhere before, but when I did a search I was overwhelmed when I put in ''crown angle'', but got nothing back when I put in ''crown angle fire''!

I know that crown angles and pav angles affect the look of a diamond even when they are within the ''ideal'' margins.

Am I correct in assuming that if you get more white light you get less fire and vice versa? Or can you have high scores in both?

I''ve been looking at J colour rb stones after reading all the glowing reports from people on here who have gone with a J. However, I''m looking for something that has a good cut so that it still looks pretty white face up (no surprise there!)!

Someone mentioned that increased fire can make a darker stone look more coloured. Is that true? I must admit that I really like the coloured flashes that come off a diamond, but at the same time don''t want the stone to look YELLOW.

I''d be really grateful if someone could give me an idiots version of how c and p angles alter the appearence of a diamond!

Thanks in advance!

 

[Rhino]

Hi jl,

Scroll on down for the answers to your questions.

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On 8/29/2004 10:05:30 AM just_looking! wrote:











I'm sure that this has been answered somewhere before, but when I did a search I was overwhelmed when I put in 'crown angle', but got nothing back when I put in 'crown angle fire'!

I know that crown angles and pav angles affect the look of a diamond even when they are within the 'ideal' margins.

Yep.

Am I correct in assuming that if you get more white light you get less fire and vice versa?

Nope.

Or can you have high scores in both?

Yes. I would add this qualifying question though ... in what light conditions are we talking?

You see ... there are diamonds on the market that have incredible fire when observed in direct light conditions (ie. jewelery store lighting, halogens, sunlight, etc.) yet when you take those stones into more suffuse light conditions (fluorescent, office lighting, cloudy day conditions) can appear darker and less bright. These are diamonds that we have found to be of a "shallow/shallow" combination of angles. Ie. if pavilion angles are too shallow and coupled with crown angles that are also on the shallow side it causes too much head obstruction in those light conditions affecting the brightness or brilliance of the diamond in those conditions.

There are however certain *sweet spots* where you can maximize both fire (in direct light conditions) and brilliance (in suffuse light conditions) and there are seperate tests for each which you can read about in our tutorial on cut. Our selection process considers the results of both and not just one.

I've been looking at J colour rb stones after reading all the glowing reports from people on here who have gone with a J. However, I'm looking for something that has a good cut so that it still looks pretty white face up (no surprise there!)!

Smart man. I will even purchase and sell "K" colors if they pass our optical exams.

Someone mentioned that increased fire can make a darker stone look more coloured. Is that true?

Actually *all*colors (D-K) tend to take on a darker appearance in direct light conditions making it very difficult to differentiate between the colors. What becomes apparent in those light conditions however is the diamond with the superior fire.

I must admit that I really like the coloured flashes that come off a diamond, but at the same time don't want the stone to look YELLOW.

I'd be really grateful if someone could give me an idiots version of how c and p angles alter the appearence of a diamond!

Thanks in advance!
----------------

Hrm... well... while crown/pavilion angles have a great affect on the appearance I would add that lower girdles also greatly affect the appearance just as much. I have examples of this in our tutorial on the minor facets. Regarding the "shallow/shallow" combinations and the "steep/deep" combinations of crown/pavilion angles I can photograph the steep/deeps for ya but I may not have any shallow/shallows in stock to do so to show you. I am off today and tomorrow but if you send me a reminder email for Tuesday I'll post pics that demonstrate these optical differences.

Regards,

 

[SLH]

Rhino,

Can you explain the results of this stone? What is it about this stone that causes it to perform well on the brilliant scope with only a 6.6% crown height? I have viewed countless branded princess cut stones and non branded stones that fall into the AGA 1A category, but do not achieve three VH’s.

 

[SLH]

B-Scope results.

 

[Upgradable]

I'm in the same boat as just_looking. I'm leaning toward a J stone, ideal cut, mounted in a two-tone setting. Are BrilliantScope results a good screening for "lively" stones? Should I look for VH on white light and lower scores on brilliance?

BTW- thanks to all of you for supporting this venue. I know now what info to seek when I say I'm looking for quality!

 

[just_looking!]

Thanks Rhino!

I'm off to look at GOG's tome of online information on cut.

I'm turning into a diamond bore according to my boyfriend....

Tee Hee! He says that he draws the line when I start looking at Platinum alloy mixes and comparing the relative merits.

Nothing new there - I'm the same when researching holidays, clothes (the list goes on....)!

Must be the scientist background?

 

[just_looking!]

I've read that Pavilion Angles of more than 41 deg can seriously impact on light return. Using AGS scale as a guideline allows up to 41.5 deg.

Is the 41.0 deg a useful cut off point or should I be a bit more technical? Can having a 41.0 deg pav can be rescued by an X deg crown angle?

 

[mdx]

Just looking

Try playing with the HCA (Cut Adviser) for some interesting results

johan