What Characteristics Will This Diamond Likely Display?

[FANTASTIC FOX]

Hello all,

I have a diamond that I am considering but I am a little concerned about the lower girdle percentage being a little on the short side.

Can anyone help shed some light on what characteristics a diamond will have with theses proportions? I am curious how the Crown/Table/Star Facets will interact with the Pavilion & Lower Girdle.

Table %: 54.8
Depth %: 61.9
Crown % 15.7
Crown Angle: 34.8
Star %: 54
Pav Angle: 40.8
Pavillion %: 42.9
Lower Girdle %: 75.6

Thanks for taking a look.

 

[bmfang]

Specs are in the sweet spot. A 75% LGF will exhibit “fatter” arrows as the pavilion mains will be larger. Stone should have larger flashes of fire as a result.

Specs on that stone are good.

 

[rockysalamander]

The shorter LGF will mean you will have chubby and not skinny arrows. I like right around 75% for myself. They improve contrast, which I find is a good thing.

LGF 75% (all other number quite close to yours)



LGF 80%

 

[FANTASTIC FOX]

Would it be correct to assume that the chubbier arrows causing the larger flashes would be a trade off on scintillation?

How do the star facets come into play here? They are on the 55% side of things instead of 50%. I guess it would help the overall brightness? Once again, probably leading to bigger flashes compared to scintillation?

Specs are in the sweet spot. A 75% LGF will exhibit “fatter” arrows as the pavilion mains will be larger. Stone should have larger flashes of fire as a result.

Specs on that stone are good.

 

[rockysalamander]

https://www.whiteflash.com/about-diamonds/diamond-education/facets-the-lower-halves.htm

 

[Dancing Fire]

Very nice specs! if you like fatter arrows.

 

[OoohShiny]

Would it be correct to assume that the chubbier arrows causing the larger flashes would be a trade off on scintillation?

How do the star facets come into play here? They are on the 55% side of things instead of 50%. I guess it would help the overall brightness? Once again, probably leading to bigger flashes compared to scintillation?

Chubbier arrows create broader reflections, which mean that visible fire is increased - the 'fan' of the spectrum of colours that reflected white light splits into is larger, therefore meaning that each coloured element within it is larger, which means your eyes have more chance of seeing each individual element (colour) as it passes over your eyes, rather than your eyes seeing all the colours at once and perceiving the reflection as sparkle/white light return.

So I think you might be right - scintillation (AIUI) is the effect of one eye seeing white light and the other seeing no light, your brain therefore seeing the flash as brighter. If the white light is split into its constituent parts and one eye sees colour (rather than white), is that scintillation? I'm not sure - that is a question for @Serg!

If I am right, and scintillation is only caused by white light rather than coloured fire, then the answer to your first question would be 'yes' - but I would note that coloured fire is still very attractive


re: the Star Facets, John does mention them here, but I'm sure there is a lot more to cover about them!
https://www.pricescope.com/community/threads/which-cbi-0-5-e-vs1.240494/#post-4335138

 

[FANTASTIC FOX]

Chubbier arrows create broader reflections, which mean that visible fire is increased - the 'fan' of the spectrum of colours that reflected white light splits into is larger, therefore meaning that each coloured element within it is larger, which means your eyes have more chance of seeing each individual element (colour) as it passes over your eyes, rather than your eyes seeing all the colours at once and perceiving the reflection as sparkle/white light return.

So I think you might be right - scintillation (AIUI) is the effect of one eye seeing white light and the other seeing no light, your brain therefore seeing the flash as brighter. If the white light is split into its constituent parts and one eye sees colour (rather than white), is that scintillation? I'm not sure - that is a question for @Serg!

If I am right, and scintillation is only caused by white light rather than coloured fire, then the answer to your first question would be 'yes' - but I would note that coloured fire is still very attractive


re: the Star Facets, John does mention them here, but I'm sure there is a lot more to cover about them!
https://www.pricescope.com/community/threads/which-cbi-0-5-e-vs1.240494/#post-4335138

Thank you Shiny.

This is actually very helpful and is interesting. After reading your response, I think I realize I may be considering scintillation incorrectly. I thought it only described the volume, size and rate of the sparkle. I believe my personal taste for a diamond would lean towards more smaller flashes rather than fewer large size flashes. Obviously something in the middle would be the most ideal. I never really considered the color spectrum to be related to scintillation. I thought it was completely separate and hence being referred to as fire.

I read the link you sent and John's feedback describing the 3 dimensional dance regarding all the proportions working together. It probably has a lot to do with the proportions of the diamond I am referring to. It seems like all the dimensions are at the edge of the ideal PS ranges.

Table: 54.8% (A little bit on the smaller side of PS ideal)
Crown Angle: 34.8 (A little bit on the higher side of PS ideal)
Lower Girdle: 75.6% (A little bit on the smaller side of PS ideal)
Star: 54%: (A little bit on the higher side of PS ideal)
Depth: 61.9 (A little bit on the higher side of PS ideal)
Pavilion: 42.9 (A little bit on the higher side of PS ideal)

I was having a difficult time putting all the cuts together and understanding if they are complementary or if they aren't and the diamond would possess a certain nuance.

 

[Texas Leaguer]

Chubbier arrows create broader reflections, which mean that visible fire is increased - the 'fan' of the spectrum of colours that reflected white light splits into is larger, therefore meaning that each coloured element within it is larger, which means your eyes have more chance of seeing each individual element (colour) as it passes over your eyes, rather than your eyes seeing all the colours at once and perceiving the reflection as sparkle/white light return.

So I think you might be right - scintillation (AIUI) is the effect of one eye seeing white light and the other seeing no light, your brain therefore seeing the flash as brighter. If the white light is split into its constituent parts and one eye sees colour (rather than white), is that scintillation? I'm not sure - that is a question for @Serg!

If I am right, and scintillation is only caused by white light rather than coloured fire, then the answer to your first question would be 'yes' - but I would note that coloured fire is still very attractive

Scintillation is the dynamic on/off optical character of a diamond in motion. It involves both white and colored sparkles. (flash scintillation and fire scintillation). You can have scintillation that is low on fire or a fiery stone without a high degree of overall scintillation. Having a good mix of large and small virtual facets with the proper amount and distribution of structured contrast is important to both flash and fire, and to achieving an optimal balance. This overview article contains links to AGS research.
https://www.whiteflash.com/about-di...sparkle-the-secrets-of-scintillation-1367.htm

 

[OoohShiny]

Scintillation is the dynamic on/off optical character of a diamond in motion. It involves both white and colored sparkles. (flash scintillation and fire scintillation). You can have scintillation that is low on fire or a fiery stone without a high degree of overall scintillation. Having a good mix of large and small virtual facets with the proper amount and distribution of structured contrast is important to both flash and fire, and to achieving an optimal balance. This overview article contains links to AGS research.
https://www.whiteflash.com/about-di...sparkle-the-secrets-of-scintillation-1367.htm

Many thanks for the input, TL, it is much appreciated!

I'll have to add that report to my reading list!

 

[OoohShiny]

I believe my personal taste for a diamond would lean towards more smaller flashes rather than fewer large size flashes

You might want to look at something like Solasfera diamonds - they have more facets, creating more and smaller reflections, therefore creating more white light return and 'sparkle'.

If they are not to your taste, look for something with longer Lower Girdle Facets (LGFs) - 75% to 80% is the usual range in MRBs (IIRC), and the 80% end will have narrower 'arrows' that also help create smaller reflections.

It probably has a lot to do with the proportions of the diamond I am referring to. It seems like all the dimensions are at the edge of the ideal PS ranges.

Table: 54.8% (A little bit on the smaller side of PS ideal)
Crown Angle: 34.8 (A little bit on the higher side of PS ideal)
Lower Girdle: 75.6% (A little bit on the smaller side of PS ideal)
Star: 54%: (A little bit on the higher side of PS ideal)
Depth: 61.9 (A little bit on the higher side of PS ideal)
Pavilion: 42.9 (A little bit on the higher side of PS ideal)

I was having a difficult time putting all the cuts together and understanding if they are complementary or if they aren't and the diamond would possess a certain nuance.

Have you run these figures through the Holloway Cut Advisor (HCA) tool in the Tools tab at the top of the forum?

42.9 is very deep when compared to the PS-recommended range of 40.6 to 40.9 (again, IIRC...), and even 0.1 degrees can make a massive difference.

If 42.9 is not a typo, I think the stone will very definitely be a 'steep/deep' (steep crown, deep pavilion), meaning it will hide a lot of weight that you can't see (because it will face up smaller than a well-cut stone of the same carat weight).

 

[rockysalamander]

Specs at the top suggest a nice well-balanced stone. For me, it is in all my "sweet spots" of the ranges. This is exactly the kind of stone we hope to find for posters unless they really want a 60/60 style or super-ideal. Can you share the weight, diameter, and price? That might help us tell you if visual aside, this is competitively priced.

Table %: 54.8
Depth %: 61.9
Crown % 15.7
Crown Angle: 34.8
Star %: 54
Pav Angle: 40.8
Pavillion %: 42.9
Lower Girdle %: 75.6

 

[tyty333]

You might want to look at something like Solasfera diamonds - they have more facets, creating more and smaller reflections, therefore creating more white light return and 'sparkle'.

If they are not to your taste, look for something with longer Lower Girdle Facets (LGFs) - 75% to 80% is the usual range in MRBs (IIRC), and the 80% end will have narrower 'arrows' that also help create smaller reflections.



Have you run these figures through the Holloway Cut Advisor (HCA) tool in the Tools tab at the top of the forum?

42.9 is very deep when compared to the PS-recommended range of 40.6 to 40.9 (again, IIRC...), and even 0.1 degrees can make a massive difference.

If 42.9 is not a typo, I think the stone will very definitely be a 'steep/deep' (steep crown, deep pavilion), meaning it will hide a lot of weight that you can't see (because it will face up smaller than a well-cut stone of the same carat weight).

I think OP is mixing % and degrees Oh Shiny. At the top he said the Pav was 40.8 (I'm assuming degrees). Also said Pav was 42.9%.

FANTASTIC FOX - just FYI, when we have actual degrees we use the degree values because they are more accurate then percentages.
You crown/pav combo in degrees is (34.8/40.8 )..which is good.

 

[FANTASTIC FOX]

Specs at the top suggest a nice well-balanced stone. For me, it is in all my "sweet spots" of the ranges. This is exactly the kind of stone we hope to find for posters unless they really want a 60/60 style or super-ideal. Can you share the weight, diameter, and price? That might help us tell you if visual aside, this is competitively priced.

Table %: 54.8
Depth %: 61.9
Crown % 15.7
Crown Angle: 34.8
Star %: 54
Pav Angle: 40.8
Pavillion %: 42.9
Lower Girdle %: 75.6

Sorry for the delay, It's been crazy at work.

To clarify if there was confusion: The Pavilion angle is 40.8 and the pavilion percentage is 42.9.

The stone is 1.64 carat. Dimensions 7.61x7.56. The depth is not listed yet. it is an advance selection and they are getting back to me on it. They did confirm the other dimensions though.

I am assuming the depth will be between 4.65 and 4.67. So it will face up a little smaller for a 1.6 but not a deal breaker.

It is a "J" color, internally flawless. The wire price is $12,036.


I do like the Solasfera but I think it is probably a little overkill. All the diamonds I have viewed in person have always had LGF of 77 or 78 and star percentages of 50-51. Also tables around 55-57.

I just was having a hard time imagining what a smaller table, shorter lower girdle and longer star facets would look like. However, there has been some great feedback here so I am getting a grasp of it. Just a couple of weeks and I should get this bad boy in person.