Sarin report/Angles advice please.

[Bluehammer]

Hello,

I have been looking for a while for a diamond. I would prefer to get the best ideal cut that I can afford. I have a pretty good understanding of color and clarity, but I need some more info on cut. I am aware of a "sweet spot" range on table and depth %. Also there seems to be a "sweet spot" for crown and pavilion angles. But in the end, it is the naked eye visual performance that speaks to an individual.

My question centers around the crown and pavilion angles. I see on the Sarin report that these angles are really an average. Therefore, would I get better light return (ie better cut) if I look for angles that are in the "sweet spot" for ideal cut, but have less of a difference in min. and max. angles? Is the better light return in a stone the result of smaller differences in these angles?

Example for crown angles:
34.0 - 35.0 would be worse than 34.4 - 34.6? Both average 34.5.

Thanks for any input. I realize that each diamond is unique and there are always exceptions to the rule. I am just trying to narrow down my search on paper before I have some stones pulled for review. Thanks again.

 

[strmrdr]

There are 2 schools of thought on this:

1: tight diamonds return more light because all the facets are working together.

2: slight variation increase scintillation due to the reflectors being pointed in slightly different directions as long as the facets don''t cross over a critical angle.

Funny thing is that both schools are likely right in my opinion.
My own feelings are that I love tight diamonds from a workmanship point of view and as long as its not too extreme there isn''t a huge/(any?) performance penalty to slightly more variation unless some of the facets cross over a critical angle.

 

[pricescope]

Bluehammer, sometimes it is important to check the average angles of the opposite facets. E.g. if a diamond has a 1 degree tilted table, Sarin can report crown and pavilion angles vary 1 degree while they can have the same angle to each other and the girdle.

check out Brian''s post this topic: DiamCalc Request

 

[Ellen]

Blue, while you could certainly stick to the sweet spots to stay safe, if you can see an IS of the diamond, that will tell you a lot, along with looking at the variances in angles.

I have a 34/41 Not something the majority around here would go with. But the IS was perfect, and it's EXTREMELY tight cut. It's outstanding.

Diamondseeker did a thread recently where she bought 2 stones to compare. One was in the sweet spot, and one was cut with practically the same angles as mine (also by the same company, Isee2, they cut great stones). She couldn't see a difference, and ultimately picked the one she did for size, not performance.

Hope this helps.

 

[Paul-Antwerp]

Hi Bluehammer,

You have asked a very interesting question, and I will try to give you my view in a second.

However, before I go into answering your question, I prefer to correct the incomplete answers of others. I hope that you do not mind.

Live long,

 

[pricescope]

Date: 7/24/2006 10:49:54 AM
Author: Paul-Antwerp

However, before I go into answering your question, I prefer to correct the incomplete answers of others. I hope that you do not mind.

Thank you, Paul. It will be much appreciated.

 

[Paul-Antwerp]

Date: 7/24/2006 9:50:47 AM
Author: strmrdr
There are 2 schools of thought on this:

1: tight diamonds return more light because all the facets are working together.

2: slight variation increase scintillation due to the reflectors being pointed in slightly different directions as long as the facets don''t cross over a critical angle.

Funny thing is that both schools are likely right in my opinion.
My own feelings are that I love tight diamonds from a workmanship point of view and as long as its not too extreme there isn''t a huge/(any?) performance penalty to slightly more variation unless some of the facets cross over a critical angle.

I think that the problem is that there are NO schools of thought on this, at least there is no true scientific verification of various theories. The reason is rather simple, introducing all separate variables into a predictive model would make the model so complicated that nobody has the resources to work it out.

Storm''s first mentioned school is exactly my thinking. The direction of light is predictable, and the tighter a diamond is cut, the more predictable that light return is. Now, when one is maximizing light return, it is a lot easier to do that with predictable measurements, than with unpredictable ones. Therefore, my theory is that a tighter cut stone will always outperform a stone with the same average measurements, but less tightly cut. No, I should rephrase this, this is probably true in the high performance-end of stones.

As for your point 2, I do not understand it. When observed, a stone is divided in a multitude of virtual facets. The tighter a diamond is cut, the more crisp the division is between these virtual facets. Crispness will make the on-off-effect of scintillation easier to observe, I should think.

Live long,

 

[Paul-Antwerp]

Date: 7/24/2006 9:59:32 AM
Author: Pricescope
Bluehammer, sometimes it is important to check the average angles of the opposite facets. E.g. if a diamond has a 1 degree tilted table, Sarin can report crown and pavilion angles vary 1 degree while they can have the same angle to each other and the girdle.

check out Brian''s post this topic: DiamCalc Request

Very true, but this is truly an exception to the rule.

If the table is tilted after all other parts of the stone were finished OR if the table was tilted on the Sarin-machine, because of some dirt on the platform, this may occur. However, in that case, both the pavilion and the crown should show the same distortion. If it is only in one of the two parts, there is no hidden tightness.

It may also be the result of dirt in the tang when polishing, but on a stone of a certain size and cut for light performance, one can expect that it is measured after each partial cutting-operation. It is highly unlikely that it would pass through to the market in that case.

Live long,

 

[Paul-Antwerp]

Date: 7/24/2006 10:08:54 AM
Author: Ellen
Blue, while you could certainly stick to the sweet spots to stay safe, if you can see an IS of the diamond, that will tell you a lot, along with looking at the variances in angles.

I have a 34/41 Not something the majority around here would go with. But the IS was perfect, and it''s EXTREMELY tight cut. It''s outstanding.

Diamondseeker did a thread recently where she bought 2 stones to compare. One was in the sweet spot, and one was cut with practically the same angles as mine (also by the same company, Isee2, they cut great stones). She couldn''t see a difference, and ultimately picked the one she did for size, not performance.

Hope this helps.

It is exactly Blue''s point that the sweet spot is probably not everything and that variances also have a role.

Let us assume a sweet spot of 34.5/40.7 and compare it to a stone with average 34.5/41.0. Popular agreement would be that number 1 should outperform number 2.

However, if stone number one has a pavilion ranging from 40.3 to 41.2, and number 2 a pavilion ranging from 40.9 to 41.0, which one will be the best performer? It is my guess that number 2 will be better. Maybe.

Who knows where the trade-off between tightness and sweet-spot actually is. I am sure that there definitely is one, but I cannot quantify it.

Live long,

 

[Paul-Antwerp]

Date: 7/24/2006 9:36:42 AM
Author:Bluehammer
Hello,

I have been looking for a while for a diamond. I would prefer to get the best ideal cut that I can afford. I have a pretty good understanding of color and clarity, but I need some more info on cut. I am aware of a ''sweet spot'' range on table and depth %. Also there seems to be a ''sweet spot'' for crown and pavilion angles. But in the end, it is the naked eye visual performance that speaks to an individual.

My question centers around the crown and pavilion angles. I see on the Sarin report that these angles are really an average. Therefore, would I get better light return (ie better cut) if I look for angles that are in the ''sweet spot'' for ideal cut, but have less of a difference in min. and max. angles? Is the better light return in a stone the result of smaller differences in these angles?

Example for crown angles:
34.0 - 35.0 would be worse than 34.4 - 34.6? Both average 34.5.

Thanks for any input. I realize that each diamond is unique and there are always exceptions to the rule. I am just trying to narrow down my search on paper before I have some stones pulled for review. Thanks again.

Blue,

As you can gather from my answers above, any reply to your questions cannot be clear-cut.

It is my true belief that tight cutting, combined with the sweet spot of averages produces the ultimate light performance in a round brilliant. However, going away from the sweet-spot, or going away from the tight cutting, I do not know which has the most negative effect. Theories, I do have, but I must say that theory is not always practice.

However, you should always remember to put more emphasis on the correctness of the pavilion than on the correctness of the crown. The pavilion is the foundation, and one cannot build a house without a good foundation.

Live long,

 

[Ellen]

Date: 7/24/2006 11:27:04 AM
Author: Paul-Antwerp

Date: 7/24/2006 10:08:54 AM

Author: Ellen

Blue, while you could certainly stick to the sweet spots to stay safe, if you can see an IS of the diamond, that will tell you a lot, along with looking at the variances in angles.


I have a 34/41 Not something the majority around here would go with. But the IS was perfect, and it''s EXTREMELY tight cut. It''s outstanding.


Diamondseeker did a thread recently where she bought 2 stones to compare. One was in the sweet spot, and one was cut with practically the same angles as mine (also by the same company, Isee2, they cut great stones). She couldn''t see a difference, and ultimately picked the one she did for size, not performance.


Hope this helps.

It is exactly Blue''s point that the sweet spot is probably not everything and that variances also have a role.


Let us assume a sweet spot of 34.5/40.7 and compare it to a stone with average 34.5/41.0. Popular agreement would be that number 1 should outperform number 2.


However, if stone number one has a pavilion ranging from 40.3 to 41.2, and number 2 a pavilion ranging from 40.9 to 41.0, which one will be the best performer? It is my guess that number 2 will be better. Maybe.


Who knows where the trade-off between tightness and sweet-spot actually is. I am sure that there definitely is one, but I cannot quantify it.


Live long,

Hi Paul, enjoy your posts.

Well, I thought that''s what I was implying, as I did say, "if you can see an IS of the diamond, that will tell you a lot, along with looking at the variances". But maybe I didn''t word it well. I guess what I meant to say was, if one couldn''t see an IS and Sarin, it could be safer to stick in the so called sweet zone, but yes, as you pointed out, if one can see how tightly cut a stone is, the "less desirable" may actually be the better performing stone.