is light return "everything"?

[bluefire7]

hi all! from an idealscope image which shows all leakage, can you definitively tell that the cut will be a great cut? for example, say you''re comparing 2 IS images, 1 shows a very nice diamond with very little leakage, as compared with an H&A or equivalent IS. is it ALL about the light return of a diamond (which can be measured by imagescope) which predictably makes a good performing diamond? all assuming you cannot see the diamond in person, of course...

 

[Dreamer_D]

I''m sorry, I am not totally sure what you are asking?

An IS allows you to see how the diamond is returning light. Combined with a good cert as well as a photo of the actual diamond, I think this is all you really need to know to pick a winner.

 

[stone-cold11]

No, also patterning, contrast, which is all you can tell from an idealscope. It will not tell you how a stone perform for fire and scintillation.

 

[Rockdiamond]

Date: 1/13/2010 5:19:07 PM
Author:bluefire7
hi all! from an idealscope image which shows all leakage, can you definitively tell that the cut will be a great cut? for example, say you're comparing 2 IS images, 1 shows a very nice diamond with very little leakage, as compared with an H&A or equivalent IS. is it ALL about the light return of a diamond (which can be measured by imagescope) which predictably makes a good performing diamond? all assuming you cannot see the diamond in person, of course...

A great question.
I feel a lot of stones get knocked for "leakage" when that aspect might be what's attractive to some viewers.
It really comes down to preference, yet sometimes reading online, it seems as though it's cut and dried. "Stone A has leakage under the table, stone B does not, so stone B is "better"
Both stones in my hypothetical example are GIA EX cut grades, so both could be said to be well cut.
Some people will prefer the stone that is knocked for leakage.

 

[Dancing Fire]

Date: 1/13/2010 5:47:22 PM
Author: Rockdiamond

Date: 1/13/2010 5:19:07 PM
Author:bluefire7
hi all! from an idealscope image which shows all leakage, can you definitively tell that the cut will be a great cut? for example, say you''re comparing 2 IS images, 1 shows a very nice diamond with very little leakage, as compared with an H&A or equivalent IS. is it ALL about the light return of a diamond (which can be measured by imagescope) which predictably makes a good performing diamond? all assuming you cannot see the diamond in person, of course...

A great question.
I feel a lot of stones get knocked for ''leakage'' when that aspect might be what''s attractive to some viewers.
It really comes down to preference, yet sometimes reading online, it seems as though it''s cut and dried. ''Stone A has leakage under the table, stone B does not, so stone B is ''better''
Both stones in my hypothetical example are GIA EX cut grades, so both could be said to be well cut.
Some people will prefer the stone that is knocked for leakage.

RD...you are the only person that prefers a "leaking stone"

 

[denverappraiser]

Date: 1/13/2010 7:51:43 PM
Author: Dancing Fire

Date: 1/13/2010 5:47:22 PM

Author: Rockdiamond

Date: 1/13/2010 5:19:07 PM

Author:bluefire7

hi all! from an idealscope image which shows all leakage, can you definitively tell that the cut will be a great cut? for example, say you're comparing 2 IS images, 1 shows a very nice diamond with very little leakage, as compared with an H&A or equivalent IS. is it ALL about the light return of a diamond (which can be measured by imagescope) which predictably makes a good performing diamond? all assuming you cannot see the diamond in person, of course...

A great question.

I feel a lot of stones get knocked for 'leakage' when that aspect might be what's attractive to some viewers.

It really comes down to preference, yet sometimes reading online, it seems as though it's cut and dried. 'Stone A has leakage under the table, stone B does not, so stone B is 'better'

Both stones in my hypothetical example are GIA EX cut grades, so both could be said to be well cut.

Some people will prefer the stone that is knocked for leakage.

RD...you are the only person that prefers a 'leaking stone'

No, he’s not. He’s just the most vocal about it here. What get’s called ‘leakage’ here is an attribute that increases contrast in the stone and the areas of light transmission will change depending on both the viewing angle and the angle of the light from the source. As it is moved these angles change and the changing light & dark areas are what gives it life. Imagine the IS image of a rhinestone or a foil backed piece of glass. Leakage will be zero. That doesn’t make it better even though the light return is 100%.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[rparker1998]

Date: 1/13/2010 8:24:20 PM
Author: denverappraiser

Date: 1/13/2010 7:51:43 PM
Author: Dancing Fire

Date: 1/13/2010 5:47:22 PM

Author: Rockdiamond

Date: 1/13/2010 5:19:07 PM

Author:bluefire7

hi all! from an idealscope image which shows all leakage, can you definitively tell that the cut will be a great cut? for example, say you''re comparing 2 IS images, 1 shows a very nice diamond with very little leakage, as compared with an H&A or equivalent IS. is it ALL about the light return of a diamond (which can be measured by imagescope) which predictably makes a good performing diamond? all assuming you cannot see the diamond in person, of course...

A great question.

I feel a lot of stones get knocked for ''leakage'' when that aspect might be what''s attractive to some viewers.

It really comes down to preference, yet sometimes reading online, it seems as though it''s cut and dried. ''Stone A has leakage under the table, stone B does not, so stone B is ''better''

Both stones in my hypothetical example are GIA EX cut grades, so both could be said to be well cut.

Some people will prefer the stone that is knocked for leakage.

RD...you are the only person that prefers a ''leaking stone''

No, he’s not. He’s just the most vocal about it here. What get’s called ‘leakage’ here is an attribute that increases contrast in the stone and the areas of light transmission will change depending on both the viewing angle and the angle of the light from the source. As it is moved these angles change and the changing light & dark areas are what gives it life. Imagine the IS image of a rhinestone or a foil backed piece of glass. Leakage will be zero. That doesn’t make it better even though the light return is 100%.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

Mr. Beaty,

Based on your logic above, then what "good" is an IS image then? If a non-leakage diamond doesn''t necessarily perform any better than a leaking diamond, then why bother with an IS at all? (Maybe = because i''m just learning, i don''t understand the true value of an IS and leakage here except that "a well cut stone will perform better than a poorly cut stone".....) Please do enlighten me. I am a sponge and what I wouldn''t give for a weeks tutilage under some of the knowledgeable people on PS.....

Regards,
Rparker1998

 

[stone-cold11]

Leakage is associated with increase carat weight, thus increasing the price of the stone sold. So why do I want to pay for the extra weight that leads to light not being return when a well cut stone will leak less with correct the faceting can still results in good scintillation instead of relying on leakage for contrast effect?

 

[diagem]

Date: 1/13/2010 8:43:38 PM
Author: Stone-cold11
Leakage is associated with increase carat weight, thus increasing the price of the stone sold. So why do I want to pay for the extra weight that leads to light not being return when a well cut stone will leak less with correct the faceting can still results in good scintillation instead of relying on leakage for contrast effect?

Sorry S-c, but not always...
it can also be associated with the spread factor (shallower cuts tend to leak more)
I agree with both Neil & RD on this one..., light return is only part of the beauty equation....

 

[denverappraiser]

Date: 1/13/2010 8:40:39 PM
Author: rparker1998
Mr. Beaty,

Based on your logic above, then what ''good'' is an IS image then? If a non-leakage diamond doesn''t necessarily perform any better than a leaking diamond, then why bother with an IS at all? (Maybe = because i''m just learning, i don''t understand the true value of an IS and leakage here except that ''a well cut stone will perform better than a poorly cut stone''.....) Please do enlighten me. I am a sponge and what I wouldn''t give for a weeks tutilage under some of the knowledgeable people on PS.....

Regards,

Rparker1998

I do think the Idealscope is a useful tool for evaluating diamonds. I have one and use it routinely. It’s just not a matter of purely evaluating light return. What the IS is showing is the ability of a stone to collect light from horizon to horizon and reflect it back up the central axis of the stone. This is a good thing, it’s just not the ONLY thing, which is the topic of this thread. Tilt a stone even slightly and the image you see in an IS is very different and the term ‘leakage’ can be very confusing. It is not all transmitted through the stone and out the pavilion as the name suggests (some is). When a stone moves, as it always does in normal types of viewing environment, some of the facets seen to be leaking will become reflectors and some of the others will become transmitters. This switching between light and dark areas in the stone is part of the beauty and how much of that is deemed desirable has a huge component of taste. I’ve got no problem with stones that are cut to maximize the IS image, actually I rather like them, but it’s not correct to say that people with different tastes are wrong and it’s not correct to say that RD is the only one out there with different taste.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[ericad]

Many people love antique cuts. I bet they leak light like crazy (never checked via IS) but so many people love them and think they are stunning, and they were certainly not cut for maximum light return! So it's a matter of taste and preference - I'd choose a leaky OEC over a precision cut modern RB any day of the week and so would a lot of people. As I understand it, this is the point RD and Neil and Diagem are trying to make - maximum light return is not the only gauge of beauty. But if a buyer decides that it's what they want in a diamond, then tools like IS and ASET and HCA become very useful. But they aren't always relevant to every buyer.

 

[IceExplorer]

Date: 1/13/2010 5:25:27 PM
Author: Stone-cold11
No, also patterning, contrast, which is all you can tell from an idealscope. It will not tell you how a stone perform for fire and scintillation.

Stone,
What is the best tool for Fire and Scintillation? The Gemex Scan?

 

[stone-cold11]

Fire, scint, you will have to use your eyes. Maybe with a full sarin scan, Diamcalc can do some prediction.